power: supply: Make bd9995x_chip_reset static

Fix the following sparse warning:

drivers/power/supply/bd99954-charger.c:1028:6: warning: symbol 'bd9995x_chip_reset' was not declared.

The bd9995x_chip_reset() has only one call site within bd99954-charger.c
It should be static

Fixes: 0902f83664 ("power: supply: Support ROHM bd99954 charger")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Samuel Zou <zou_wei@huawei.com>
Reviewed-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/bd99954-charger.c

@@ -1025,7 +1025,7 @@ static int bd9995x_fw_probe(struct bd9995x_device *bd)
 	return 0;
 }
 
-void bd9995x_chip_reset(void *bd)
+static void bd9995x_chip_reset(void *bd)
 {
 	__bd9995x_chip_reset(bd);
 }