gpio: sh-pfc: fix gpio input read

Fix gpio_read: gpio input (INDT) and gpio output (OUTDT) registers
have different offset. gpio_read must be performed from INDT.

Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>