drm/xe/vm: Remove VM_BIND_OP macro

This macro was necessary when bind operations were shifted but this
is no longer the case, so removing to simplify code.

Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>