mfd: stmpe: Staticise stmpe_of_probe()

It is only called from this file so there is no need for it to be in the
global namespace and cause sparse to warn.

Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/stmpe.c

@@ -1106,7 +1106,8 @@ static int stmpe_devices_init(struct stmpe *stmpe)
 	return ret;
 }
 
-void stmpe_of_probe(struct stmpe_platform_data *pdata, struct device_node *np)
+static void stmpe_of_probe(struct stmpe_platform_data *pdata,
+			   struct device_node *np)
 {
 	struct device_node *child;