iser-target: Ignore non TEXT + LOGOUT opcodes for discovery

This patch adds a check in isert_rx_opcode() to ignore non TEXT + LOGOUT
opcodes when SessionType=Discovery has been negotiated.

Cc: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --cc drivers/infiniband/ulp/isert/ib_isert.c
Simple merge