scsi: ips: Convert strnlen() to memcpy() since result should not be NUL terminated

Fixes the following W=1 kernel build warning(s):

 In file included from arch/arm/include/asm/io.h:23,
 from drivers/scsi/ips.c:164:
 In function ‘strncpy’,
 inlined from ‘ips_send_cmd’ at drivers/scsi/ips.c:3522:6:
 include/linux/string.h:297:30: warning: ‘__builtin_strncpy’ output
 truncated before terminating nul cop ying 4 bytes from a string of the same length [-Wstringop-truncation]
 297 | #define __underlying_strncpy __builtin_strncpy
 | ^
 include/linux/string.h:307:9: note: in expansion of macro ‘__underlying_strncpy’
 307 | return __underlying_strncpy(p, q, size);
 | ^~~~~~~~~~~~~~~~~~~~
 NB: Lots of these - snipping for brevity

Link: https://lore.kernel.org/r/20200723122446.1329773-14-lee.jones@linaro.org


Cc: Adaptec OEM Raid Solutions <aacraid@microsemi.com>
Cc: ipslinux@adaptec.com
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>