pinctrl: renesas: r8a779a0: Use shorthands for reserved fields

Replace the full descriptions of reserved register fields by shorthands
with a negative field width, and merge adjacent reserved fields.

This reduces kernel size by 140 bytes.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/807b2a7e02be2fac50c280961a4841813ab13cd8.1649865241.git.geert+renesas@glider.be