GUI: Fix typo in warning message

Change-Id: I991ad86a453273139bcafbb9f68898631dfb6b51
diff --git a/gui/Android.mk b/gui/Android.mk
index 51cf4ca..78e93c6 100644
--- a/gui/Android.mk
+++ b/gui/Android.mk
@@ -108,7 +108,7 @@
 
 ****************************************************************************
   Could not find ui.xml for TW_CUSTOM_THEME: $(TW_CUSTOM_THEME)
-  Expected to find cutom theme's ui.xml at:
+  Expected to find custom theme's ui.xml at:
     $(TWRP_THEME_LOC)/ui.xml
   Please fix this or set TW_THEME to one of the following:
     $(notdir $(wildcard $(commands_recovery_local_path)/gui/theme/*_*))