pinctrl: sh-pfc: r8a7794: Swap ATA signals

All R8A7794 manuals I have here (0.50 and 1.10) agree that the PFC driver
has ATAG0# and ATAWR0# signals in IPSR12 swapped -- fix this.

Fixes: 43c4436e ("pinctrl: sh-pfc: add R8A7794 PFC support")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>