ENGR00174904 VPU: change spinlock to mutex

ENGR00174904 VPU: change spinlock to mutex

The spinlock caused a bug warning when we enable the lock debug mechenism.

See the log:
"
BUG: sleeping function called from invalid context at mm/slub.c:847
in_atomic(): 1, irqs_disabled(): 0, pid: 6053, name: aiurdemux0:sink
INFO: lockdep is turned off.
no locks held by aiurdemux0:sink/6053.
[<80042f24>] (unwind_backtrace+0x0/0xfc) from
                                     [<800f1dec>] (kmem_cache_alloc+0x114/0x180)
[<800f1dec>] (kmem_cache_alloc+0x114/0x180) from
                                     [<800e425c>] (__get_vm_area_node+0x88/0x194)
[<800e425c>] (__get_vm_area_node+0x88/0x194) from
                                     [<800e4b78>] (__vmalloc_node_range+0x68/0x1c8)
[<800e4b78>] (__vmalloc_node_range+0x68/0x1c8) from
                                     [<800e4d18>] (__vmalloc_node+0x40/0x48)
[<800e4d18>] (__vmalloc_node+0x40/0x48) from
                                     [<800e4f04>] (vmalloc_user+0x2c/0x74)
[<800e4f04>] (vmalloc_user+0x2c/0x74) from [<8038eb28>] (vpu_ioctl+0x204/0x8b0)
[<8038eb28>] (vpu_ioctl+0x204/0x8b0) from [<8010643c>] (do_vfs_ioctl+0x80/0x5e4)
[<8010643c>] (do_vfs_ioctl+0x80/0x5e4) from [<801069d8>] (sys_ioctl+0x38/0x60)
[<801069d8>] (sys_ioctl+0x38/0x60) from [<8003d500>] (ret_fast_syscall+0x0/0x3c)
"

Change the spinlock to mutex to fix this issue.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Sammy He <r62914@freescale.com>