pinctrl: sh-pfc: r8a77970: Remove MMC_{CD,WP}

Hardware Manual Errata for rev. 1.50 of March 26, 2019 removed the bit
definitions for MMC_CD and MMC_WP in the documentation for the IPSR6 and
IPSR7 registers, as these pin functionalities do not exist on R-Car
V3M.

Remove the definitions, and the corrresponding pins and groups.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>