drm/print: Add drm_coredump_printer_is_full

Add drm_coredump_printer_is_full which indicates if a drm printer's
output is full. Useful to short circuit coredump printing once printer's
output is full.

v2:
 - s/drm_printer_is_full/drm_coredump_printer_is_full (Jani)
v3:
 - Bail if not a coredump printer (Michal)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://lore.kernel.org/r/20250423171725.597955-4-matthew.brost@intel.com