Revert "OMAP3: ack spurious IRQs in get_irqnr_and_base"

This reverts commit 3da0e10243d075b905dfa8f1b4a6cb3694ab2ce0.

The real bug behind this issue is the fact that we're not
masking out the SPURIOUSIRQFLAG bits [31:7] from the active
interrupt number. The following patch will replace this
patch with the fix.

Signed-off-by: Tony Lindgren <tony@atomide.com>