omap: gpio: Use generic API
Convert all OMAP specific functions to use the common API
definitions in include/asm/gpio.h. In the process, made
few additional changes:
- Use -EINVAL consistently. -1 was used in many places.
- Removed one-liner static functions that were used only
once. Replaced the content as necessary.
- Combines implementation of functions omap_get_gpio_dataout()
and omap_get_gpio_datain(). To do so, new static function
_get_gpio_direction() was added.
Signed-off-by: Sanjeev Premi <premi@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>