ARM: OMAP2+: clockdomain: add pwrdm_state_switch() call to clkdm_sleep()

In clkdm_sleep(), the powerdomain should be eligible to switch power
states right after the call to the low-level clockdomain sleep
function.  We should have been tracking that with the
pwrdm_state_switch() code, but we weren't, for whatever reason.  Fix that.

This resolves the "pwrdm state mismatch(cam_pwrdm) 3 != 0" that appears
during the OMAP4460 Pandaboard-ES PM test, e.g. here:

http://www.pwsan.com/omap/testlogs/test_v3.8-rc5/20130126003323/pm/4460pandaes/4460pandaes_log.txt



Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Tero Kristo <t-kristo@ti.com>