CP-17631: Don't default HVM keymap to en-us
CP-17631: Don't default HVM keymap to en-us

Xenopsd is responsible for sorting out the defaults and there's a good
reason to leave it empty as it enables QEMU's ExtendedKeyEvent
extension (see xenopsd#272).

Signed-off-by: Si Beaumont <a0992b7f1f450b4c7716d34b81a2d6f0877ae11a@citrix.com>

rafalmiel/xen-api,srowe/xen-api,rafalmiel/xen-api,rafalmiel/xen-api,thomassa/xen-api,thomassa/xen-api,srowe/xen-api,Frezzle/xen-api,thomassa/xen-api,Frezzle/xen-api,srowe/xen-api,euanh/xen-api,thomassa/xen-api,rafalmiel/xen-api,rafalmiel/xen-api,Frezzle/xen-api,euanh/xen-api,rafalmiel/xen-api,srowe/xen-api,euanh/xen-api,thomassa/xen-api,Frezzle/xen-api,euanh/xen-api,euanh/xen-api,Frezzle/xen-api,thomassa/xen-api,srowe/xen-api,euanh/xen-api