mips: dts: ralink: mt7621: use the new compatible string for MT7621 pinctrl

mips: dts: ralink: mt7621: use the new compatible string for MT7621 pinctrl

Use the new compatible string "ralink,mt7621-pinctrl" for the Ralink MT7621
pinctrl subdriver on mt7621.dtsi.

Each subdriver needs to have a different compatible string. We don't want
the same compatible string to match a different subdriver's pinmux data as
it's not for our SoC.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Acked-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20220414173916.5552-10-arinc.unal@arinc9.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>