pinctrl: renesas: checker: Validate I/O voltage configs consistency

Validate consistency of the pin control tables for pins with I/O voltage
capabilities.  If a pin has I/O voltage register bits declarations
through .pin_to_pocctrl(), the SH_PFC_PIN_CFG_IO_VOLTAGE flag should be
set in the pin's configs, and vice versa.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/de81cced01ae3f26d341177d66d4b8e918fbfb76.1640270559.git.geert+renesas@glider.be