Building GENERIC64 on aarch64 fails

[Adam <adam%netbsd.org@localhost>]

/dist/src/sys/dev/ic/com.c: In function 'com_attach_subr':
/dist/src/sys/dev/ic/com.c:593:21: error: 'vm_guest' undeclared (first use in this function)
  593 |                 if (vm_guest == VM_GUEST_NO)
      |                     ^~~~~~~~
/dist/src/sys/dev/ic/com.c:593:21: note: each undeclared identifier is reported only once for each function it appears in
/dist/src/sys/dev/ic/com.c:593:33: error: 'VM_GUEST_NO' undeclared (first use in this function)
  593 |                 if (vm_guest == VM_GUEST_NO)
      |                                 ^~~~~~~~~~~
--- com.o ---

*** Failed target: com.o
*** In directory: /dist/work/obj.aarch64/sys/arch/evbarm/compile/GENERIC64


I see VM_GUEST_NO is defined only for x86 in src/sys/arch/x86/include/cpu.h.

Please, fix.
Adam