platform/x86: intel_scu_ipc: Drop unused prototype intel_scu_ipc_fw_update()

There is no implementation for that anymore so drop the prototype.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

arch/x86/include/asm/intel_scu_ipc.h

@@ -53,9 +53,6 @@ int intel_scu_ipc_command(int cmd, int sub, u32 *in, int inlen,
 int intel_scu_ipc_raw_command(int cmd, int sub, u8 *in, int inlen,
 			      u32 *out, int outlen, u32 dptr, u32 sptr);
 
-/* Update FW version */
-int intel_scu_ipc_fw_update(u8 *buffer, u32 length);
-
 extern struct blocking_notifier_head intel_scu_notifier;
 
 static inline void intel_scu_notifier_add(struct notifier_block *nb)