pinctrl: renesas: r8a779g0: Fix (H)SCIF1 suffixes

The Pin Multiplex attachment in Rev.1.10 of the R-Car V4H Series
Hardware User's Manual still has two alternate pin groups (GP0_14-18
and GP1_6-10) each named both HSCIF1 and SCIF1.  To differentiate, the
pin control driver uses "(h)scif1" and "(h)scif1_x", which were
considered temporary names until the conflict was sorted out.

Fix this by adopting R-Car V4M naming:
  - Rename "(h)scif1" to "(h)scif1_a",
  - Rename "(h)scif1_x" to "(h)scif1_b".

Adopt the R-Car V4M naming "(h)scif1_a" and "(h)scif1_b" to increase
uniformity.

While at it, remove unneeded separators.

Fixes: ad9bb2fe ("pinctrl: renesas: Initial R8A779G0 (R-Car V4H) PFC support")
Fixes: 050442ae ("pinctrl: renesas: r8a779g0: Add pins, groups and functions")
Fixes: cf4f7891 ("pinctrl: renesas: r8a779g0: Add missing HSCIF1_X")
Fixes: 9c151c2b ("pinctrl: renesas: r8a779g0: Add missing SCIF1_X")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/5009130d1867e12abf9b231c8838fd05e2b28bee.1717754960.git.geert+renesas@glider.be