OMAP4: powerdomain: Update DSS logic state for ES2

DSS on ES2 supports only OSWR, hence remove the support
for CSWR from the powerdomain framework.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Benoît Cousson <b-cousson@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>