tests: demand_paging/mem_map: move malloc config to prj.conf

Both tests set CONFIG_COMMON_LIBC_MALLOC_ARENA_SIZE=0 so extract
it to prj.conf. The tests require malloc arena size to be 0 to
run successful. By refactoring the config, it is now able to
with west build and still passing.

Signed-off-by: Daniel Leung <[email protected]>

Author: dcpleung

tests/kernel/mem_protect/demand_paging/mem_map/prj.conf

@@ -4,3 +4,4 @@ CONFIG_DEMAND_PAGING_STATS=y
 CONFIG_DEMAND_PAGING_THREAD_STATS=y
 CONFIG_DEMAND_PAGING_TIMING_HISTOGRAM=y
 CONFIG_TEST_USERSPACE=y
+CONFIG_COMMON_LIBC_MALLOC_ARENA_SIZE=0

tests/kernel/mem_protect/demand_paging/mem_map/testcase.yaml

@@ -10,8 +10,6 @@ tests:
       - qemu_cortex_a53
       - qemu_cortex_a53/qemu_cortex_a53/smp
       - qemu_x86_tiny
-    extra_configs:
-      - CONFIG_COMMON_LIBC_MALLOC_ARENA_SIZE=0
   kernel.demand_paging.mem_map.timing_funcs:
     tags:
       - kernel
@@ -20,4 +18,3 @@ tests:
     platform_allow: qemu_x86_tiny
     extra_configs:
       - CONFIG_DEMAND_PAGING_STATS_USING_TIMING_FUNCTIONS=y
-      - CONFIG_COMMON_LIBC_MALLOC_ARENA_SIZE=0