ARM: dts: ux500: Fix STMPE device nodes

The STMPE device nodes need to be augmented to fit with current
naming policies.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230508070811.965762-1-linus.walleij@linaro.org