clk: renesas: r8a779f0: Correct PFC/GPIO parent clock

According to the R-Car S4 Series Hardware User’s Manual Rev.0.81, the
parent clock of the Pin Function (PFC/GPIO) module clock is the CP
clock.

As this clock is not documented to exist on R-Car S4, use the CPEX clock
instead.

Fixes: 73421f2 ("clk: renesas: r8a779f0: Add PFC clock")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/f88ec4aede0eaf0107c8bb7b28ba719ac6cd418f.1706197415.git.geert+renesas@glider.be

Author: geertu

drivers/clk/renesas/r8a779f0-cpg-mssr.c

@@ -161,7 +161,7 @@ static const struct mssr_mod_clk r8a779f0_mod_clks[] __initconst = {
 	DEF_MOD("cmt1",		911,	R8A779F0_CLK_R),
 	DEF_MOD("cmt2",		912,	R8A779F0_CLK_R),
 	DEF_MOD("cmt3",		913,	R8A779F0_CLK_R),
-	DEF_MOD("pfc0",		915,	R8A779F0_CLK_CL16M),
+	DEF_MOD("pfc0",		915,	R8A779F0_CLK_CPEX),
 	DEF_MOD("tsc",		919,	R8A779F0_CLK_CL16M),
 	DEF_MOD("rswitch2",	1505,	R8A779F0_CLK_RSW2),
 	DEF_MOD("ether-serdes",	1506,	R8A779F0_CLK_S0D2_HSC),