[SCSI] be2iscsi: fix memory leak in error path

There are two memory leaks in cases 'ISCSI_NET_PARAM_VLAN_ID' and
'ISCSI_NET_PARAM_VLAN_PRIORITY' and also a potential junk pointer free if
mgmt_get_if_info() returns error because if_info will be unset and it is stack
allocated.

Signed-off-by: Geyslan G. Bem <geyslan@gmail.com>
Cc: Jayamohan Kallickal <jayamohan.kallickal@emulex.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>