mmc/omap: Use disable_irq_nosync() from within irq handlers.

disable_irq() should wait for all running handlers to complete
before returning.  As such, if it's used to disable an interrupt
from that interrupt's handler it will deadlock.  This replaces
the dangerous instances with the _nosync() variant which doesn't
have this problem.

Signed-off-by: Ben Nizette <bn@niasdigital.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Pierre Ossman <pierre@ossman.eu>