pinctrl: sh-pfc: rcar-gen3: Rename SEL_ADG_{A,B,C} to SEL_ADG{A,B,C}

According to the R-Car Gen3 Hardware Manual Errata for Rev 0.80 of Dec
22, 2017, and the Errata for Rev 1.50 of Dec 25, 2018, MOD_SEL0 register
bits 3, 4, 17, and 18 are renamed from SEL_ADG_{A,B,C} to
SEL_ADG{A,B,C}.  Update the pin control drivers to reflect this.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>