clk: renesas: r8a779g0: Correct PFC/GPIO parent clocks

According to the R-Car V4H Series Hardware User’s Manual Rev.1.00, the
parent clock of the Pin Function (PFC/GPIO) module clocks is the CP
clock.

Fix this by adding the missing CP clock, and correcting the PFC parents.

Fixes: f2afa78d ("dt-bindings: clock: Add r8a779g0 CPG Core Clock Definitions")
Fixes: 36ff3660 ("clk: renesas: r8a779g0: Add PFC/GPIO clocks")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/5401fccd204dc90b44f0013e7f53b9eff8df8214.1706197297.git.geert+renesas@glider.be