OMAP clock: Add uart4_ick/fck definitions for 3630

This is only valid for omap 36xx family of chips.

Signed-off-by: Sergio Aguirre <saaguirre@ti.com>
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>