ARM: EXYNOS: Move Disabling of JPEG USE_RETENTION for exynos5250 to pmu.c

Move the Disabling of JPEG USE_RETENTION for exynos5250 to pmu.c to
make way for refactoring of pm.c and to create common functions across
exynos4 and exynos5250.

Signed-off-by: Vikas Sajjan <vikas.sajjan@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>