spi: omap2_mcspi supports wake events

Currently mcspi wake-ups are not enabled.  This might cause cases where
OMAP is not waking up on mcspi events.

Signed-off-by: Jouni Hogander <jouni.hogander@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>