ARM: OMAP2+: CM: make clkdm_hwsup operations static

These are not accessed outside the cm*.c files themselves, so make them
static.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Tested-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>