thinkpad_acpi: Remove ambiguous logging for "Unsupported brightness interface"

"Unsupported brightness interface" message gets logged on
 machines that are well supported.
Signed-off-by: Eric Curtin <ericcurtin17@gmail.com>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

drivers/platform/x86/thinkpad_acpi.c

@@ -6653,18 +6653,16 @@ static void __init tpacpi_detect_brightness_capabilities(void)
 	switch (b) {
 	case 16:
 		bright_maxlvl = 15;
-		pr_info("detected a 16-level brightness capable ThinkPad\n");
 		break;
 	case 8:
 	case 0:
 		bright_maxlvl = 7;
-		pr_info("detected a 8-level brightness capable ThinkPad\n");
 		break;
 	default:
-		pr_info("Unsupported brightness interface\n");
 		tp_features.bright_unkfw = 1;
 		bright_maxlvl = b - 1;
 	}
+	pr_debug("detected %u brightness levels\n", bright_maxlvl + 1);
 }
 
 static int __init brightness_init(struct ibm_init_struct *iibm)