Mateusz Junkier

After Zephyr changes in commit [af974c30747 ](https://github.com/zephyrproject-rtos/zephyr/commit/af974c307477f4e0e093abbfca768419f14a865f)replace removed IMR_L3_HEAP_SIZE to ace_imr_get_mem_size(). This fixes build error : zephyr/lib/alloc.c:220:27: error: 'IMR_L3_HEAP_SIZE' undeclared (first use in this function)