scsi: esas2r: Use flex array destination for memcpy()

scsi: esas2r: Use flex array destination for memcpy()

In preparation for FORTIFY_SOURCE performing run-time destination buffer
bounds checking for memcpy(), specify the destination output buffer
explicitly, instead of asking memcpy() to write past the end of what looked
like a fixed-size object. Silences future run-time warning:

  memcpy: detected field-spanning write (size 80) of single field "trc + 1" (size 64)

There is no binary code output differences from this change.

Link: https://lore.kernel.org/r/20220901205729.2260982-1-keescook@chromium.org
Cc: Bradley Grove <linuxdrivers@attotech.com>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>