x86, vdso, xen: Remove stray reference to FIX_VDSO

Checkin

b0b49f2673f0 x86, vdso: Remove compat vdso support

... removed the VDSO from the fixmap, and thus FIX_VDSO; remove a
stray reference in Xen.

Found by Fengguang Wu's test robot.

Reported-by: Fengguang Wu <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Konrad Rzeszutek Wilk <[e-mail]>
Cc: Boris Ostrovsky <[e-mail]>
Cc: David Vrabel <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: H. Peter Anvin <[e-mail]>

arch/x86/xen/mmu.c

···
 	case FIX_RO_IDT:
 #ifdef CONFIG_X86_32
 	case FIX_WP_TEST:
-	case FIX_VDSO:
 # ifdef CONFIG_HIGHMEM
 	case FIX_KMAP_BEGIN ... FIX_KMAP_END:
 # endif