[Keyboard] Add define GPIO into Dosa40RGB (#15252)

Co-authored-by: NOOB Maker <93704375+noobmakers@users.noreply.github.com>

keyboards/dtisaac/dosa40rgb/keymaps/default/keymap.c

@@ -67,3 +67,8 @@ void rgb_matrix_indicators_user(void)
 		rgb_matrix_set_color(22, 200, 0, 200);
 	}
 }
+
+void keyboard_pre_init_user(void) {
+    setPinOutput(B5);
+    writePinLow(B5);
+}