OMAP3 PM: Defining .pwrsts_logic_ret field for core power domain structure

This patch adds the flag .pwrsts_logic_ret info for the core power domain
in the associated powerdomain structure. This flag specifies the states
core domain logic can hit in event of the domain entering retention.

Signed-off-by: Thara Gopinath <thara@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>