sh-pfc: Add support for sparse pin numbers

The PFC driver assumes that the value of the GPIO_PORTxxx enumeration
names are equal to the port number. This isn't true when the port number
space is sparse, as with the SH73A0.

Fix the issue by adding support for pin numbers ranges specified through
SoC data. When no range is specified the driver considers that the PFC
implements a single contiguous range for all pins.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>