scsi: lpfc: fix 32-bit format string warning

On 32-bit architectures, we see a warning when %ld is used to print a
size_t:

In file included from drivers/scsi/lpfc/lpfc_init.c:62:
drivers/scsi/lpfc/lpfc_init.c: In function 'lpfc_new_io_buf':
drivers/scsi/lpfc/lpfc_logmsg.h:62:45: error: format '%ld' expects argument of type 'long int', but argument 5 has type 'unsigned int' [-Werror=format=]

This is harmless, but portable code should just use %zd to avoid the
warning.

Fixes: 0794d601

 ("scsi: lpfc: Implement common IO buffers between NVME and SCSI")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>