target: Drop unnecessary t_state_lock access for SCF_SUPPORTED_SAM_OPCODE assignment

This patch drops the se_cmd->t_state_lock access around SCF_SUPPORTED_SAM_OPCODE
assignment within target_setup_cmd_from_cdb().

Original v4.0 target code required this as fabrics would be checking for
this values in different process contexts for setup and I/O submission.

Given that modern v4.1 target code performs setup and I/O submission
from the same process context, this t_state_lock access is no longer
required.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Cc: Moussa Ba <moussaba@micron.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>