tests: Increase testcases timeout for fvp_baser_aemv8r_smp

The tests/kernel/mem_protect/syscalls/ and tests/kernel/smp/ run too
slow on fvp_baser_aemv8r_smp. Increase the timeout_multiplier to 8 for
fvp_baser_aemv8r_smp.

Signed-off-by: Jaxson Han <[email protected]>

Author: povergoing

boards/arm64/fvp_baser_aemv8r/fvp_baser_aemv8r_smp.yaml

@@ -10,3 +10,5 @@ toolchain:
   - cross-compile
 ram: 2048
 flash: 64
+testing:
+  timeout_multiplier: 8