complete: fix parameter complete with multiple '.'

When a device parameter has dots in its name, we have to use strchr instead
of strrchr, because the devicename ends at the first dot, not at the last one.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

common/complete.c

@@ -221,7 +221,7 @@ static int env_param_complete(struct string_list *sl, char *instr, int eval)
 		end = ' ';
 	}
 
-	instr_param = strrchr(instr, '.');
+	instr_param = strchr(instr, '.');
 	len = strlen(instr);
 
 	current_c = get_current_context();