Fix bad parameter names in error message (#3129)

diff --git a/utils/generate_grammar_tables.py b/utils/generate_grammar_tables.py
index 06fcf94..943d0d1 100755
--- a/utils/generate_grammar_tables.py
+++ b/utils/generate_grammar_tables.py
@@ -774,8 +774,8 @@
          args.extinst_debuginfo_grammar and
          args.extinst_cldebuginfo100_grammar):
         print('error: --operand-kinds-output requires --spirv-core-grammar '
-              'and --exinst-debuginfo-grammar '
-              'and --exinst-cldebuginfo100-grammar')
+              'and --extinst-debuginfo-grammar '
+              'and --extinst-cldebuginfo100-grammar')
         exit(1)
     if (args.glsl_insts_output is None) != \
             (args.extinst_glsl_grammar is None):