MAINTAINERS: add tools/misc/xen-cpuid to "X86 ARCHITECTURE"

Along the lines of other x86-specific pieces under tools/.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wl@xen.org>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>

MAINTAINERS

@@ -472,6 +472,7 @@ F:	tools/firmware/rombios/
 F:	tools/firmware/vgabios/
 F:	tools/fuzz/cpu-policy/
 F:	tools/fuzz/x86_instruction_emulator/
+F:	tools/misc/xen-cpuid.c
 F:	tools/tests/cpu-policy/
 F:	tools/tests/x86_emulator/