ARM: OMAP: gpio-switch.c: use right flags for interrupts

The recent switch from SA_ to IRQF_ constants for interrupt flags
introduced a typo in the gpio_switch driver (IRQF_SHIRQ doesn't exist
but IRQF_SHARED does).

Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>