pinctrl: sh-pfc: r8a77965: Add TPU pins, groups and functions

Add pins, groups and functions for the 16-Bit Timer Pulse Unit outputs
on the R-Car M3-N SoC.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>