thinkpad-acpi: R52 brightness_mode has been confirmed

We can stop pestering users for confirmation of the brightness_mode
default for firmware TP-76.

While at it, add a few missing comments in that quirk table.
Reported-by: NWhoopie <whoopie79@gmx.net>
Signed-off-by: NHenrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: stable@kernel.org

drivers/platform/x86/thinkpad_acpi.c

@@ -6139,13 +6139,13 @@ static const struct tpacpi_quirk brightness_quirk_table[] __initconst = {
 	TPACPI_Q_IBM('1', 'Y', TPACPI_BRGHT_Q_EC),	/* T43/p ATI */
 
 	/* Models with ATI GPUs that can use ECNVRAM */
-	TPACPI_Q_IBM('1', 'R', TPACPI_BRGHT_Q_EC),
+	TPACPI_Q_IBM('1', 'R', TPACPI_BRGHT_Q_EC),	/* R50,51 T40-42 */
 	TPACPI_Q_IBM('1', 'Q', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_EC),
-	TPACPI_Q_IBM('7', '6', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_EC),
+	TPACPI_Q_IBM('7', '6', TPACPI_BRGHT_Q_EC),	/* R52 */
 	TPACPI_Q_IBM('7', '8', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_EC),
 
 	/* Models with Intel Extreme Graphics 2 */
-	TPACPI_Q_IBM('1', 'U', TPACPI_BRGHT_Q_NOEC),
+	TPACPI_Q_IBM('1', 'U', TPACPI_BRGHT_Q_NOEC),	/* X40 */
 	TPACPI_Q_IBM('1', 'V', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_EC),
 	TPACPI_Q_IBM('1', 'W', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_EC),