Revert "ARM: OMAP: Mask interrupts when disabling interrupts, v2"

This reverts commit 5461af5a.

Adding a disable hook to the irq_chip is not the way to fix the
problem being addressed by this patch.  Instead, we need to fix
support for [enable|disable]_irq_wake().

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>