[BUG] TLB driver fails to unmap L2 HPSRAM region when assertions are enabled

[marcinszkudlinski]

Describe the bug
When Zephyr assertions are enabled, TLB driver assertion fails at:
zephyr\drivers\mm\mm_drv_common.c:179
__ASSERT(false, "cannot unmap %p\n", va);
It looks like size of the region to unmap is bigger than expected.

Some debugging info:
int ret2 = sys_mm_drv_unmap_page(va); ret2 = -22;
uint8_t *va = 0xa0161000
void *virt = 0xa0161000
size_t size = 7073792
CONFIG_KERNEL_VM_BASE = 0xa0020000
CONFIG_KERNEL_VM_SIZE = 0x800000

To Reproduce

Add CONFIG_ASSERT=y to SOF\app\boards\intel_adsp_ace15_mtpm.conf
Run the FW on FPGA & connect with debugger
Reproduction Rate
100%

Expected behavior
TLB driver unmaps L2 HPSRAM memory correctly.

Impact
Annoyance, but quick fix is advised so we can finally enable assertions for MTL.