ARM: OMAP: DRA7: powerdomain data: Remove wrong OSWR capability

Open Switch Retention(OSWR) is a retention state which is unsupported
in DRA7 SoC. This state is achieved when power state is set to
retention and logic power state is set to OFF.

Even though DRA7 architecture is a OMAP derivative, none of the
powerdomains are actually implemented to achieve OSWR in the SoC.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>