pinctrl: sh-pfc: Rename 2-parameter CPU_ALL_PORT() variant

There are two variants of the CPU_ALL_PORT() macro in use:
  1. A three-parameter variant, to be provided for SoCs with a linear
     GPIO pin space ("PORT style"),
  2. A two-parameter variant, to be provided for SoCs with 32-port GPIO
     banks ("GP port style").

Rename the 2-parameter variant to CPU_ALL_GP(), to avoid confusion, and
to increase naming consistency.

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