ARM: dts: stm32: stm32mp157c-phycore: Fix STMPE811 touchscreen node properties

ARM: dts: stm32: stm32mp157c-phycore: Fix STMPE811 touchscreen node properties

Move st,adc-freq, st,mod-12b, st,ref-sel, and st,sample-time properties
from the touchscreen subnode to the parent touch@44 node. These properties
are defined in the st,stmpe.yaml schema for the parent node, not the
touchscreen subnode, resolving the validation error about unevaluated
properties.

Fixes: 27538a18a4fcc ("ARM: dts: stm32: add STM32MP1-based Phytec SoM")
Signed-off-by: Jihed Chaibi <jihed.chaibi.dev@gmail.com>
Link: https://lore.kernel.org/r/20250915224611.169980-1-jihed.chaibi.dev@gmail.com
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>