ARM: dts: stm32mp15: remove hwlocks from pinctrl

Removes hwlocks properties from stm32mp151 pinctrl node. These locks
could be used for other purpose, depending on board and software
configuration hence do not enforce their use to protect pinctrl
devices.

This patch is an alignment with Linux device tree with v6.0 as the
hwsem support wasn’t yet added in pincontrol in kernel. It avoids
issues when the Linux kernel is started with the U-Boot device tree.

Cc: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: Patrick Delaunay <patrick.delaunay@foss.st.com>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>