ARM: shmobile: add common extra gpio functions

Current gpio frame work doesn't have the method to control
just pull up/down/free, but some SH-ARM boards need such kind of operation.
This patch adds common extra gpio functions for 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>