fix typo

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>

scripts/mbedtls_framework/c_build_helper.py

@@ -12,7 +12,7 @@
 import tempfile
 
 class CompileError(Exception):
-    """Excetion to represent an error during the compilation."""
+    """Exception to represent an error during the compilation."""
 
     def __init__(self, message):
         """Save the error massage"""