ARM: shmobile: use common extra gpio functions on g4evm

This patch switch over to use common extra gpio method,
and reduced a waste of code on SH-ARM.

But these functions should be replaced by correct
gpio function in the future.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>