drivers: target: Mark functions and structures as static in tfc_conf.c

Mark functions ft_tpg_alloc_fabric_acl(), ft_register_configfs() and
ft_deregister_configfs() as static in tcm_fc/tfc_conf.c because they are
not used outside this file.

This eliminates the following warnings in tcm_fc/tfc_conf.c:
drivers/target/tcm_fc/tfc_conf.c:270:21: warning: no previous prototype for ‘ft_tpg_alloc_fabric_acl’ [-Wmissing-prototypes]
drivers/target/tcm_fc/tfc_conf.c:555:5: warning: no previous prototype for ‘ft_register_configfs’ [-Wmissing-prototypes]
drivers/target/tcm_fc/tfc_conf.c:602:6: warning: no previous prototype for ‘ft_deregister_configfs’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>