ARM: OMAP: GPIO: Fix valid range and enable usage of all GPIOs on OMAP5

The omap_gpio driver is used by AM33XX, OMAP3/4, OMAP54XX and DRA7XX SoCs.
These SoCs have different gpio count but currently omap_gpio driver uses hard
coded 192 which is wrong.

This patch fixes this issue by:
1. Move define of OMAP_MAX_GPIO to all arch/arm/include/asm/arch-omap*/gpio.h.
2. Update gpio bank settings and enable GPIO modules 7 & 8 clocks for OMAP5.

Thanks for Lubomir Popov to provide valuable comments to fix this issue.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Tested-by: Lubomir Popov <lpopov@mm-sol.com>
Acked-by: Heiko Schocher <hs@denx.de>