drm/xe/uapi: Use common drm_xe_ext_set_property extension

There really is no difference between 'struct drm_xe_ext_vm_set_property'
and 'struct drm_xe_ext_exec_queue_set_property', they are extensions which
specify a <property, value> pair. Replace the two extensions with a single
common 'struct drm_xe_ext_set_property' extension. The rationale is that
rather than have each XE module (including future modules) invent their own
property/value extensions, all XE modules use a common set_property
extension when possible.

Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
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>