ARM: OMAP3: PM: Fix the Invalid CM_CLKSTCTRL reg access.

In OMAP2/3 some of the clock-domains which did not have control
facility were being falsely written to and read using the CM_CLKSTCTRL
register though it did not exist for them. One check is added to remove
this flaw.

Signed-off-by: Abhijit Pagare <abhijitpagare@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Rajendra Nayak <rnayak@ti.com>