PM / devfreq: fix typo "CPU_EXYNOS4.12" twice

Dependencies on CPU_EXYNOS4212 and CPU_EXYNOS4412 for the "ARM
Exynos4210/4212/4412 Memory Bus DEVFREQ Driver" were added in commit
7b405038 ("PM/Devfreq: Add Exynos4-bus
device DVFS driver for Exynos4210/4212/4412."). The tree (at that time,
v3.3, and currently) makes clear that this should have been dependencies
on SOC_EXYNOS4212 and SOC_EXYNOS4412.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>