pinctrl: sh-pfc: Allow compile-testing of all drivers

pinctrl: sh-pfc: Allow compile-testing of all drivers

Enable compile-testing of all Renesas SuperH and ARM pin control
drivers, in a similar way as was done before for clock and SoC drivers
in commits 371dd373c6edd557 ("clk: renesas: Allow compile-testing of all
(sub)drivers") and 8be381a131c29c47 ("soc: renesas: Rework Kconfig and
Makefile logic").

The SuperH pin control drivers need specific include files, hence make
sure they are always found when compile-testing.

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