In preparation for a generic GPIO driver for the DA8xx processors,
rename <asm/arch/gpio_defs.h> to <asm/arch/gpio.h> and fix up all files
which include it.

Signed-off-by: Laurence Withers <lwithers@guralp.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>