target: Convert inquiry temporary buffer to heap memory

This patch converts the temporary buffer in spc_emulate_inquiry() to
use dynamically allocated memory, instead of local stack memory.

Also bump SE_INQUIRY_BUF up to 1024 bytes to be safe when handling
multiple large SCSI name descriptors for EVPD=0x83.

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>