wifi: mt76: mt7915: Remove unused of_gpio.h

of_gpio.h is deprecated and subject to remove.
The driver doesn't use it, simply remove the unused header.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7915/soc.c

@@ -7,7 +7,6 @@
 #include <linux/pinctrl/consumer.h>
 #include <linux/of.h>
 #include <linux/of_reserved_mem.h>
-#include <linux/of_gpio.h>
 #include <linux/iopoll.h>
 #include <linux/reset.h>
 #include <linux/of_net.h>