ARM: OMAP: Mask interrupts when disabling interrupts, v2

By Ingo Molnar, interrupts are not masked by default.
(refer to 76d21601

)

But if interrupts are not masked, the processor can wake up while in
Suspend-to-RAM state by an external interrupt. For example, if an
OMAP3 board is connected to Host PC by USB and entered to Suspend-to-RAM
state, it wake up automatically by M_IRQ_92. The disable_irq() function
can't disable the interrupt in H/W level, So I modified
arch/arm/mach-omap2/irq.c

Signed-off-by: Kim Kyuwon <chammoru@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>