x86/VisWS: remove Kconfig quirk

VisWS has this quirk currently:

 config X86_VISWS
 	bool "SGI 320/540 (Visual Workstation)"
	depends on X86_32 && PCI && !X86_VOYAGER && X86_MPPARSE && PCI_GODIRECT

The !Voyager quirk is unnecessary.

Signed-off-by: Ingo Molnar <mingo@elte.hu>