Fix wrong source file list in CMake of GCC_ARM_CM0 port. (#1045)

Add GCC/ARM_CM0/mpu_wrappers_v2_asm.c and GCC/ARM_CM0/portasm.c as source files to 'freertos_kernel_port' library.
This fixes the FREERTOS_PORT "GCC_ARM_CM0" CMake configuration.

portable/CMakeLists.txt

diff --git a/portable/CMakeLists.txt b/portable/CMakeLists.txt
index af9321e..819e2c1 100644
--- a/portable/CMakeLists.txt
+++ b/portable/CMakeLists.txt
@@ -77,7 +77,9 @@
 
     # ARMv6-M port for GCC
     $<$<STREQUAL:${FREERTOS_PORT},GCC_ARM_CM0>:
-        GCC/ARM_CM0/port.c>
+        GCC/ARM_CM0/port.c
+        GCC/ARM_CM0/portasm.c
+        GCC/ARM_CM0/mpu_wrappers_v2_asm.c>
 
     # ARMv6-M / Cortex-M0 Raspberry PI RP2040 port for GCC
     $<$<STREQUAL:${FREERTOS_PORT},GCC_RP2040>: