PRCM: Combine 34xx l3_icks and l4_icks

E.g dss_l3_ick and dss_l4_ick have same gating control. Having own
clock for both of them causes race condition between enable / disable.

This patch combines this kind of clocks and names new clock as <module>_ick.

Signed-off-by: Jouni Hogander <jouni.hogander@nokia.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>