drm/ttm: replace drm_print.h include with a forward declaration

drm/ttm: replace drm_print.h include with a forward declaration

The ttm/ttm_resource.h header does not really need anything from
drm_print.h. A simple forward declaration for struct drm_printer is
sufficient.

An explicit drm_print.h include has previously been added to all the
files that indirectly depended on this include.

v3: Only remove the include here (Thomas)

Cc: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/cfdb1095033112c2a7e58767481c98929984a33c.1761734313.git.jani.nikula@intel.com