platform/x86: thinkpad_acpi: Add 2nd Fan Support for Thinkpad P50

The Thinkpad P50 has 2 fans. Add the 2FAN quirk so the tpacpi driver
properly reports both fan speeds.
Because the P50 doesn't report the version of its EC controller,
we need to identify it by BIOS version (N1).
Signed-off-by: Alexander Kappner <agk@godking.net>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
[andy: renamed macro, massaged changelog]
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/thinkpad_acpi.c

@@ -8699,16 +8699,24 @@ static const struct attribute_group fan_attr_group = {
 	  .ec = TPID(__id1, __id2),		\
 	  .quirks = __quirks }
 
+#define TPACPI_FAN_QB(__id1, __id2, __quirks)	\
+	{ .vendor = PCI_VENDOR_ID_LENOVO,	\
+	  .bios = TPID(__id1, __id2),		\
+	  .ec = TPACPI_MATCH_ANY,		\
+	  .quirks = __quirks }
+
 static const struct tpacpi_quirk fan_quirk_table[] __initconst = {
 	TPACPI_FAN_QI('1', 'Y', TPACPI_FAN_Q1),
 	TPACPI_FAN_QI('7', '8', TPACPI_FAN_Q1),
 	TPACPI_FAN_QI('7', '6', TPACPI_FAN_Q1),
 	TPACPI_FAN_QI('7', '0', TPACPI_FAN_Q1),
 	TPACPI_FAN_QL('7', 'M', TPACPI_FAN_2FAN),
+	TPACPI_FAN_QB('N', '1', TPACPI_FAN_2FAN),
 };
 
 #undef TPACPI_FAN_QL
 #undef TPACPI_FAN_QI
+#undef TPACPI_FAN_QB
 
 static int __init fan_init(struct ibm_init_struct *iibm)
 {