arm64: imx8ulp: Split SRAM0 mapping to isolate the SCMI shared memory as non-cacheable

arm64: imx8ulp: Split SRAM0 mapping to isolate the SCMI shared memory as non-cacheable

This patch splits the 2MB SRAM0 mapping into three regions:
- 0x22000000~0x2201f000: cacheable normal memory
- 0x2201f000~0x22020000: non-cacheable device memory
- 0x22020000~0x22200000: cacheable normal memory

The change ensures the SCMI shared memory is non-cacheable, which
avoids cache-related issues after removing
mmu_set_region_dcache_behaviour() from scmi_dt_get_smt_buffer().

Signed-off-by: Alice Guo <alice.guo@nxp.com>
Reviewed-by: Marek Vasut <marek.vasut@mailbox.org>