gpio: Replace ARM gpio.h with the common API in include/asm-generic

gpio: Replace ARM gpio.h with the common API in include/asm-generic

ARM boards should use the generic GPIO API
This means changing gpio to unsigned type
Remove the unused gpio_toggle() function which is not part of the API
Comment that free should not modify pin state

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Cc: Joe Hershberger <joe.hershberger@gmail.com>
fixed merge conflict in da8xx_gpio.c, tegra2_gpio.c, and
extended to the new mxs_gpio.c.

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>