staging: tidspbridge: Remove OMAP_PM_SRF

The symbol is an orphan, get rid of it.

Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: Omar Ramirez Luna <omar.ramirez@copitl.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>