modpost: fix modpost warnings for xtensa

Suppress warnings for two informational sections (.xt.lit and .xt.prop)
used by the Xtensa architecture.
Signed-off-by: NMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NChris Zankel <chris@zankel.net>

scripts/mod/modpost.c

@@ -827,6 +827,8 @@ static const char *section_white_list[] =
 	".note*",
 	".got*",
 	".toc*",
+	".xt.prop",				 /* xtensa */
+	".xt.lit",         /* xtensa */
 	NULL
 };