pinctrl: renesas: r8a779g0: Fix (H)SCIF3 suffixes

(H)SCIF instance 3 has two alternate pin groups: "hscif3" and
"hscif3_a", resp. "scif3" and "scif3_a", but the actual meanings of the
pins within the groups do not match.

Increase uniformity by adopting R-Car V4M naming:
  - Rename "hscif3_a" to "hscif3_b",
  - Rename "hscif3" to "hscif3_a",
  - Rename "scif3" to "scif3_b".

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: 213b7132 ("pinctrl: renesas: r8a779g0: Add missing HSCIF3_A")
Fixes: 49e46976 ("pinctrl: renesas: r8a779g0: Add missing SCIF3")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/61fdde58e369e8070ffd3c5811c089e6219c7ecc.1717754960.git.geert+renesas@glider.be