pinctrl: sh-pfc: r8a7791: Fix IPSR comment typos

The IPSR field names in the comments have been fat-fingered in a couple
places --  fix those silly typos...

Fixes: 50884519 ("pinctrl: sh-pfc: r8a7791 PFC support")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>