scsi: sssraid: Replace zero-length array with flexible array member

Replace the zero-length array 'event_data[0]' with a C99 flexible array
member 'event_data[]' in struct sssraid_fwevt.

Zero-length arrays are a GNU extension that predates C99 flexible array
members. The kernel's fortify-string checks treat zero-length arrays as
having size 0, which causes false-positive warnings when memcpy() is used
to copy data into them:

  In function 'fortify_memcpy_chk',
    inlined from 'sssraid_process_admin_cq.isra' at
    drivers/scsi/sssraid/sssraid_fw.c:1574:3:
  ./include/linux/fortify-string.h:597:25: error: call to
  '__write_overflow_field' declared with attribute warning: detected
  write beyond size of field (1st parameter); maybe use struct_group()?

This is part of the ongoing effort to replace all zero-length arrays with
flexible array members, as recommended by the kernel coding style.

Link: KSPP/linux#78
Signed-off-by: WangYuli <wangyl5933@chinaunicom.cn>

Author: Avenger-285714

drivers/scsi/sssraid/sssraid.h

@@ -293,7 +293,7 @@ struct sssraid_fwevt {
 	bool process_evt;
 	u32 evt_ctx;
 	struct kref ref_count;
-	char event_data[0] __aligned(4);
+	char event_data[] __aligned(4);
 };
 
 /*