ARM: EXYNOS: Fix compiler error with THIS_MODULE

  CC      arch/arm/mach-exynos/cpuidle.o
arch/arm/mach-exynos/cpuidle.c:36: error: 'THIS_MODULE' undeclared here (not in a function)
arch/arm/mach-exynos/cpuidle.c: In function 'exynos4_enter_idle':
arch/arm/mach-exynos/cpuidle.c:42: error: storage size of 'before' isn't known
arch/arm/mach-exynos/cpuidle.c:42: error: storage size of 'after' isn't known
arch/arm/mach-exynos/cpuidle.c:46: error: implicit declaration of function 'do_gettimeofday'
arch/arm/mach-exynos/cpuidle.c:52: error: 'USEC_PER_SEC' undeclared (first use in this function)
arch/arm/mach-exynos/cpuidle.c:52: error: (Each undeclared identifier is reported only once
arch/arm/mach-exynos/cpuidle.c:52: error: for each function it appears in.)
arch/arm/mach-exynos/cpuidle.c:42: warning: unused variable 'after'
arch/arm/mach-exynos/cpuidle.c:42: warning: unused variable 'before'
make[1]: *** [arch/arm/mach-exynos/cpuidle.o] Error 1

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
[kgene.kim@samsung.com: Fixed as per Stephen's suggestion]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>