ARM: dts: stm32: remove shmem for scmi-optee on stm32mp13

CFG_STM32MP1_SCMI_SHM_SYSRAM will be disabled by default for STM32MP13x
SoCs in future OP-TEE version and the OP-TEE SMCI server uses only
the OP-TEE native shared memory registered by clients.

To be compatible by default with this configuration this patch removes
the shared memory in the SCMI configuration and the associated reserved
memory in SRAM.

Fixes: 9005aeddd9fc ("ARM: dts: stm32: enable optee firmware and SCMI support on STM32MP13")
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>