target: Remove unnecessary *cdb transport_get_lun_for_cmd parameter

This patch removes the now unnecessary 'unsigned char *cdb' function
parameter from transport_get_lun_for_cmd().  This also includes updating
lio-target, tcm_loop and tcm_fc usage of transport_get_lun_for_cmd().

Reported-by: Fubo Chen <fubo.chen@gmail.com>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>