xen: Drop includes of xen/hvm/params.h

xen: Drop includes of xen/hvm/params.h

xen-mapcache.c doesn't needs params.h.

xen-hvm.c uses defines available in params.h but so is xen_common.h
which is included before. HVM_PARAM_* flags are only needed to make
xc_hvm_param_{get,set} calls so including only xenctrl.h, which is
where the definition the function is, should be enough.
(xenctrl.h does include params.h)

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Message-Id: <20190618112341.513-4-anthony.perard@citrix.com>