OMAP2: PRCM: fix some SHIFT macros that were actually bitmasks

After Charu's GPIO hwmod patches, GPIO initialization on N800 emits
the following messages for all GPIO banks:

omap_hwmod: gpio1: cannot be enabled (3)

This is due to OMAP24XX_ST_GPIOS_SHIFT being defined as a bitmask.
Fix this and also fix two other macros that had the same problem.

Thanks to Tony Lindgren <tony@atomide.com> for originally reporting
this bug.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Charulatha Varadarajan <charu@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>