scsi: fdomain_isa: Merge branches in fdomain_isa_match()

The *else* branch of the *if* (base) statement in fdomain_isa_match() is
immediately followed by the *if* (!base) statement. Simplify the code by
removing the unneeded *if*.

Link: https://lore.kernel.org/r/df68e341-5113-4cf2-b64c-dc1ad0b686ac@omprussia.ru


Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>