drm: panel-backlight-quirks: Log applied panel brightness quirks

drm: panel-backlight-quirks: Log applied panel brightness quirks

Currently, when a panel brightness quirk is applied, there is no log
indicating that a quirk was applied. Unwrap the drm device on its own
and use drm_info() to log when a quirk is applied.

Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
Link: https://lore.kernel.org/r/20250829145541.512671-7-lkml@antheas.dev
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
(Correct a missing -1 in the message math)
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>