[SCSI] target: Fix bogus return in transport_add_device_to_core_hba failure path

This patch removes a bogus conditional+return check within the failure path
of transport_add_device_to_core_hba().  This breakage was introduced during
the v4 conversion to remove struct se_cmd passthrough ops for INQUIRY /
READ_CAPCITY during struct se_device creation and registration process.

Reported-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>