HSI: ssi_protocol: Remove unused linux/gpio.h

linux/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>
Link: https://lore.kernel.org/r/20240508114150.958025-1-andriy.shevchenko@linux.intel.comSigned-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/hsi/clients/ssi_protocol.c

@@ -14,7 +14,6 @@
 #include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/err.h>
-#include <linux/gpio.h>
 #include <linux/if_ether.h>
 #include <linux/if_arp.h>
 #include <linux/if_phonet.h>