ARM: dts: renesas: iwg22d-sodimm: Fix stmpe node names

ARM: dts: renesas: iwg22d-sodimm: Fix stmpe node names

make dtbs_check:

    arch/arm/boot/dts/renesas/r8a7745-iwg22d-sodimm.dtb: stmpe811@44: 'stmpe_touchscreen' does not match any of the regexes: 'pinctrl-[0-9]+'
	    from schema $id: http://devicetree.org/schemas/mfd/st,stmpe.yaml#
    arch/arm/boot/dts/renesas/r8a7745-iwg22d-sodimm-dbhd-ca.dtb: stmpe811@44: 'stmpe_touchscreen' does not match any of the regexes: 'pinctrl-[0-9]+'
	    from schema $id: http://devicetree.org/schemas/mfd/st,stmpe.yaml#

Fix this by using recommended node names for the STMicroelectronics Port
Expander (STMPE) device node and its subnode.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/40536ce7ca01e5acc9ed1d595f0e3a720eeb78d7.1698228434.git.geert+renesas@glider.be