ARM: shmobile: kota2: Register pinctrl mappings for SDHI and MMCIF

Replace the GPIO-based SDHI and MMCIF pinmux configuration by pinctrl
mappings.

Board code used the non-pulled-up version of the function GPIOs, but
those are defined in the PFC driver as enabling the pull-ups anyway.
Enable pull-ups on the MMCIF data and command pins through the pinconf
API.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>