sh-pfc: r8a7790: Add SCIF2 pins configuration support

Update the pinmux configuration tables to support the SCIF2 pins
(TX2/TX2_B, RX2/RX2_B, SCK2).

Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>