rt2x00: rework RT chipset and revision determination for PCI an SOC devices.

The recent rt2800 devices are no longer really identified by their PCI
ID's, but rather by the contents of their CSR0 register. Also for the
other chipsets is the contents of this CSR0 register important.
Change the chipset determination logic to be more aligned with the rt2800
model.
Preparation for the support of rt3070 / rt3090 based devices.

Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt61pci.h b/drivers/net/wireless/rt2x00/rt61pci.h
index 6f33f7f..ab20c77 100644
--- a/drivers/net/wireless/rt2x00/rt61pci.h
+++ b/drivers/net/wireless/rt2x00/rt61pci.h
@@ -28,6 +28,13 @@
 #define RT61PCI_H
 
 /*
+ * RT chip PCI IDs.
+ */
+#define RT2561s_PCI_ID			0x0301
+#define RT2561_PCI_ID			0x0302
+#define RT2661_PCI_ID			0x0401
+
+/*
  * RF chip defines.
  */
 #define RF5225				0x0001
@@ -225,6 +232,8 @@
  * MAC_CSR0: ASIC revision number.
  */
 #define MAC_CSR0			0x3000
+#define MAC_CSR0_REVISION		FIELD32(0x0000000f)
+#define MAC_CSR0_CHIPSET		FIELD32(0x000ffff0)
 
 /*
  * MAC_CSR1: System control register.