This patch adds READ_INSERT support in target_read_prot_action() that
invokes sbc_dif_generate() when LIO is responsible for generating the
outgoing T10-PI.
Required for supporting fabrics that exchange protection information,
and would like to function with un-protected devices.
Reviewed-by: Martin Petersen <martin.petersen@oracle.com> Reviewed-by: Sagi Grimberg <sagig@mellanox.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>