xen: Kconfig: Drop reference to obsolete configs MCORE2 and MK8

Commit f388f60ca904 ("x86/cpu: Drop configuration options for early 64-bit CPUs")
removes the config symbols MCORE2 and MK8.

With that, the references to those two config symbols in xen's x86 Kconfig
are obsolete. Drop them.

Fixes: f388f60ca904 ("x86/cpu: Drop configuration options for early 64-bit CPUs")
Signed-off-by: Lukas Bulwahn <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Reviewed-by: Juergen Gross <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/x86/xen/Kconfig

···
 	select PARAVIRT_CLOCK
 	select X86_HV_CALLBACK_VECTOR
 	depends on X86_64 || (X86_32 && X86_PAE)
-	depends on X86_64 || (X86_GENERIC || MPENTIUM4 || MCORE2 || MATOM || MK8)
+	depends on X86_64 || (X86_GENERIC || MPENTIUM4 || MATOM)
 	depends on X86_LOCAL_APIC && X86_TSC
 	help
 	  This is the Linux Xen port.  Enabling this will allow the