OMAP4: PM: Do not assume clkdm supports hw transitions

omap_set_pwrdm_state today assumes a clkdm supports hw_auto
transitions and hence leaves some which do not support this
in sw wkup state preventing low power transitions.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Benoit Cousson <b-cousson@ti.com>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>