kbuild: remove *.symversions left-over

Commit 5ce2176b ("genksyms: adjust the output format to modpost")
stopped generating *.symversions files.

Remove the left-over from the .gitignore file and the 'clean' rule.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>

.gitignore

@@ -46,7 +46,6 @@
 *.so.dbg
 *.su
 *.symtypes
-*.symversions
 *.tab.[ch]
 *.tar
 *.xz

Makefile

@@ -1946,7 +1946,7 @@ clean: $(clean-dirs)
 		-o -name '*.c.[012]*.*' \
 		-o -name '*.ll' \
 		-o -name '*.gcno' \
-		-o -name '*.*.symversions' \) -type f -print \
+		\) -type f -print \
 		-o -name '.tmp_*' -print \
 		| xargs rm -rf