[ARM] 4668/1: ep93xx: implement new GPIO API

Implement new GPIO API for ep93xx platform as defined in Documentation/gpio.txt
and provide transitional __deprecated wrappers for the previous gpio_line_*
functions.

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>
Acked-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>