ibft: fix kconfig dependencies

Fix kconfig dependency warning to satisfy dependencies:

warning: (BE2ISCSI && SCSI_LOWLEVEL && PCI && SCSI && NET || ISCSI_IBFT && ISCSI_IBFT_FIND && SCSI) selects ISCSI_BOOT_SYSFS which has unmet direct dependencies (SCSI_LOWLEVEL && SCSI)

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad@kernel.org>