Remove a check that is too strict. With BIOSen that specify an IO/ctl port

Remove a check that is too strict.  With BIOSen that specify an IO/ctl port
of 0x3f2-0x3f5,0x3f7 the ports are not 7 bytes apart.  This should fix
floppy probing on such systems.  (We handle the case of adjusting for
a start of 0x3f2 -> 0x3f0 separately, although that code should still be
checked if there are still floppy problems for others.)

Tested by:	Sarunas Vancevicius <vsarunas_at_eircom.net>
MFC after:	3 days