ARM: S5PV310: Tidy init+disable clock usage and s3c24xx_register_clocks cleanup

This patch changes the clock registration code to use the s3c_register_clocks()
followed by s3c_disable_clocks() instead of the loops it was using and cleanups
the return of s3c24xx_register_clocks() because it includes it.

Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>