Fix codespell false positive

Codespell complains about 'instruct the gsize to generate a
"*.siz" file'; fix by renaming to "*.size".

Author: pbarada

arch/arm/src/common/Toolchain.defs

@@ -482,7 +482,7 @@ ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
     # instruct the exlr to dump verbose information during link procedure
     LDFLAGS += -v
 
-    # instruct the gsize to generate a "*.siz" file that contains the detailed section size
+    # instruct the gsize to generate a "*.size" file that contains the detailed section size
     LDFLAGS += -gsize
 
     ARCHOPTIMIZATION += -G -dual_debug