pinctrl: sh-pfc: Rename PINCTRL_PFC_R8A7796 to PINCTRL_PFC_R8A77960

Rename CONFIG_PINCTRL_PFC_R8A7796 for R-Car M3-W (R8A77960) to
CONFIG_PINCTRL_PFC_R8A77960, to avoid confusion with R-Car M3-W+
(R8A77961), which will use CONFIG_PINCTRL_PFC_R8A77961.

Extend the dependency of CONFIG_PINCTRL_PFC_R8A77960 from
CONFIG_ARCH_R8A7796 to CONFIG_ARCH_R8A77960, to relax dependencies for a
future rename of the SoC configuration symbol.

Rename r8a7796_pinmux_info to r8a77960_pinmux_info, as it contains an
r8a77960-based name.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20191023122955.12420-3-geert+renesas@glider.be