drm: prepend stamp space to output mode logging
drm: prepend stamp space to output mode logging

Use the STAMP_SPACE to make the output mode logging
a little nicer looking.

Signed-off-by: U. Artie Eoff <32aece0d55055227b44d04b7d0051cf3d04ee871@intel.com>
Reviewed-by: Bryce Harrington <dd437fc32dcda8cbb48d47baa844ad777493d02b@samsung.com>

jonnylamb/weston,kwm81/weston,krezovic/weston,Tarnyko/weston-xdg_surface_present,xorgy/weston,udoprog/weston,Fantu/compositor-spice,eyolfson/weston,giucam/weston,giucam/weston,mchalupa/weston,sir-murray/weston,mchalupa/weston,jonnylamb/weston,kwm81/weston,Tarnyko/weston-xdg_surface_present,Fantu/compositor-spice,xorgy/weston,krezovic/weston,Fantu/compositor-spice,eyolfson/weston,Gnurou/weston,Gnurou/weston,sir-murray/weston,udoprog/weston