ENGR00275459 mx6sl: csi/v4l: fix kernel dump when do repeated streamon/streamoff

ENGR00275459 mx6sl: csi/v4l: fix kernel dump when do repeated streamon/streamoff

When do stream on/off in pair repeatedly without close the v4l device,
the kernel dump happens:

Unable to handle kernel paging request at virtual address 00200200
pgd = c0004000
[00200200] *pgd=00000000
Internal error: Oops: 805 [#1] PREEMPT
Modules linked in:
CPU: 0    Not tainted  (3.0.35-06027-gbbea887-dirty #21)
PC is at camera_callback+0x15c/0x1c8
LR is at 0x200200
pc : [<c03747d0>]    lr : [<00200200>]    psr: 20000193
sp : c0b0fed0  ip : 00200200  fp : daf1102c
r10: daf11034  r9 : 00100100  r8 : daf11098
r7 : daf11100  r6 : daf11034  r5 : daf11000  r4 : c0b0e000
r3 : 00000000  r2 : 00000001  r1 : 00000001  r0 : daf114b8
Flags: nzCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
Control: 10c53c7d  Table: 8cc8c059  DAC: 00000015

...

Process swapper (pid: 0, stack limit = 0xc0b0e2e8)
Stack: (0xc0b0fed0 to 0xc0b10000)
fec0:                                     c0374674 822a4000 daf11000 c0b87eb4
fee0: 00000000 00000027 c0b73904 c0b305e0 00000001 c0374090 da2bbbe0 c0b0e000
ff00: 00000000 c00acc58 00000000 c0098058 00989680 c0b305e0 c0b0e000 00000000
ff20: 00000002 00000001 c0b0e000 00000000 00000000 c00acdf8 00000000 c0b0e000
ff40: 9e4e7881 c0b305e0 c0b0e000 c00aee44 c00aed9c c0b43c6c 00000027 c00ac634
ff60: 00000270 c004257c ffffffff f2a00100 00000027 c00417cc 20000000 00000006
ff80: f40c4000 00000000 c0b0e000 c0b6a924 c0b1876c c0b18764 80004059 412fc09a
ffa0: 00000000 00000000 c0063a40 c0b0ffc0 c004f758 c0042690 80000013 ffffffff
ffc0: c004266c c004294c c0b1013c 00000000 c10960c0 c00088ec c0008334 00000000
ffe0: 00000000 c00337d4 10c53c7d c0b10060 c00337d0 80008040 00000000 00000000
[<c03747d0>] (camera_callback+0x15c/0x1c8) from [<c0374090>] (csi_irq_handler+
0x7c/0x160)
[<c0374090>] (csi_irq_handler+0x7c/0x160) from [<c00acc58>] (
handle_irq_event_percpu+0x50/0x19c)
[<c00acc58>] (handle_irq_event_percpu+0x50/0x19c) from [<c00acdf8>] (
handle_irq_event+0x54/0x84)
[<c00acdf8>] (handle_irq_event+0x54/0x84) from [<c00aee44>] (handle_fasteoi_irq
+0xa8/0x160)
[<c00aee44>] (handle_fasteoi_irq+0xa8/0x160) from [<c00ac634>] (
generic_handle_irq+0x2c/0x40)
[<c00ac634>] (generic_handle_irq+0x2c/0x40) from [<c004257c>] (handle_IRQ
+0x30/0x84)
[<c004257c>] (handle_IRQ+0x30/0x84) from [<c00417cc>] (__irq_svc+0x4c/0xa8)
[<c00417cc>] (__irq_svc+0x4c/0xa8) from [<c0042690>] (default_idle+0x24/0x28)
[<c0042690>] (default_idle+0x24/0x28) from [<c004294c>] (cpu_idle+0x8c/0xc0)
[<c004294c>] (cpu_idle+0x8c/0xc0) from [<c00088ec>] (start_kernel+0x294/0x2e4)
[<c00088ec>] (start_kernel+0x294/0x2e4) from [<80008040>] (0x80008040)
Code: e88c4200 e595c030 e5858030 e8881800 (e58c8000)
---[ end trace 224150c26d2bd5f7 ]---

The root cause is cam->enc_counter is not re-initialized to 0 when calls
STREAMOFF ioctl, and then in DQBUF ioctl wait_event_interruptible_timeout()
sees the condition is true and access cam->done_q queue which has no strict
check and could be empty.

This patch adds the re-initialization and the sanity check.
Also, add the pointer check for memcpy because the destination may be
NULL on UERSPTR mode.

Signed-off-by: Robby Cai <R63905@freescale.com>