move text_backend initialization into the shell plugin

Whether a input method is used should be the responsibility
of the shell because some shells may not want to implement
an input method at all

Signed-off-by: Murray Calavera <murray.calavera@gmail.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

desktop-shell/shell.c

@@ -6676,6 +6676,9 @@ module_init(struct weston_compositor *ec,
 	if (input_panel_setup(shell) < 0)
 		return -1;
 
+	if (text_backend_init(ec) < 0)
+		return -1;
+
 	shell_configuration(shell);
 
 	shell->exposay.state_cur = EXPOSAY_LAYOUT_INACTIVE;