drivers: pinctrl: move renesas pincontrol drivers to separate directory

Moved r8a77951/r8a77961 pfc tables and funcs from soc to drivers/pfc dir.

Move all Renesas pinctrl driver source and header files to a separate
directory "renesas" and every SoC series to a separate subdirectory.

Update the MAINTAINERS file to align with the changes in the
pinctrl directory.

Signed-off-by: Mykola Kvach <mykola_kvach@epam.com>