cpufreq: interactive: fix internal_create_group failure

cpufreq: interactive: fix internal_create_group failure

when interactive governor try to register sysfs interface,
need to make sure global kobject is initialized first,
otherwise, it will cause kernel Oops:

------------[ cut here ]------------
Kernel BUG at 80128178 [verbose debug info unavailable]
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.7+ #2883
task: ab078000 ti: ab05e000 task.ti: ab05e000
PC is at internal_create_group+0x1f4/0x230
LR is at cpufreq_governor_interactive+0x114/0x4f0
pc : [<80128178>]    lr : [<8043232c>]    psr: 60000113
sp : ab05fc48  ip : 00000063  fp : aaa3a128
r10: 8093c510  r9 : aaa3a0c0  r8 : 808d5834
r7 : 00000000  r6 : ab109200  r5 : aaa3a0c0  r4 : ab109200
r3 : 808d5aa4  r2 : 808d5834  r1 : 00000000  r0 : 00000000
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
Control: 10c5387d  Table: 1000404a  DAC: 00000015
Process swapper/0 (pid: 1, stack limit = 0xab05e240)
Stack: (0xab05fc48 to 0xab060000)

Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Anson Huang <b20788@freescale.com>