arch/samd2l2:Ignore atomic warning when using clang compiler

When the toolchain does not support atomic, it will use the version implemented by NuttX (low performance version). This scenario is consistent with the original design, so we can ignore it.

see bug here:
https://bugs.llvm.org/show_bug.cgi?id=43603

Error: inode/fs_inodeaddref.c:50:7: error: large atomic operation may incur significant performance penalty; the access size (4 bytes) exceeds the max lock-free size (0  bytes) [-Werror,-Watomic-alignment]
   50 |       atomic_fetch_add(&inode->i_crefs, 1);
      |       ^
/tools/clang-arm-none-eabi/lib/clang/17/include/stdatomic.h:152:43: note: expanded from macro 'atomic_fetch_add'
  152 | #define atomic_fetch_add(object, operand) __c11_atomic_fetch_add(object, operand, __ATOMIC_SEQ_CST)
      |                                           ^
1 error generated.
make[1]: *** [Makefile:83: fs_inodeaddref.o] Error 1
Error: inode/fs_inodefind.c:74:7: error: large atomic operation may incur significant performance penalty; the access size (4 bytes) exceeds the max lock-free size (0  bytes) [-Werror,-Watomic-alignment]
   74 |       atomic_fetch_add(&node->i_crefs, 1);

Signed-off-by: chenrun1 <chenrun1@xiaomi.com>

arch/arm/src/cmake/Toolchain.cmake

@@ -61,6 +61,8 @@ if(CONFIG_ARCH_TOOLCHAIN_CLANG)
   # https://github.com/apache/incubator-nuttx/pull/5971
 
   add_compile_options(-fno-builtin)
+  add_compile_options(-Wno-atomic-alignment)
+  add_compile_options(-Wno-atomic-alignment)
 else()
   set(TOOLCHAIN_PREFIX arm-none-eabi)
   set(CMAKE_LIBRARY_ARCHITECTURE ${TOOLCHAIN_PREFIX})

arch/arm/src/common/Toolchain.defs

@@ -324,6 +324,8 @@ endif
 
 ifeq ($(CONFIG_ARCH_TOOLCHAIN_CLANG),y)
   ARCHOPTIMIZATION += -fshort-enums
+  ARCHCFLAGS += -Wno-atomic-alignment
+  ARCHCXXFLAGS += -Wno-atomic-alignment
 endif
 
 # Architecture flags