scsi: fnic: fix format string overflow warning

The MSI interrupt name can require 11 bytes in addition to the device name,
for a total of 23 bytes:

drivers/scsi/fnic/fnic_isr.c: In function 'fnic_request_intr':
drivers/scsi/fnic/fnic_isr.c:192:4: error: '-fcs-rq' directive writing 7 bytes into a region of size between 5 and 16 [-Werror=format-overflow=]
    "%.11s-fcs-rq", fnic->name);
drivers/scsi/fnic/fnic_isr.c:206:3: note: 'sprintf' output between 12 and 23 bytes into a destination of size 16
   sprintf(fnic->msix[FNIC_MSIX_ERR_NOTIFY].devname,
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    "%.11s-err-notify", fnic->name);

This extends the buffer to fit any possible value.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>