pinctrl: sh-pfc: rcar-gen3: Retain TDSELCTRL register across suspend/resume

The TDSELCTRL register is responsible for configuring the SDHI/MMC clock
return path delay and may be adjusted by the bootloader. Retain the value
across suspend/resume to prevent hardware instability after resume.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>