NET_SB1250_MAC: Update Kconfig entry

The SB1250 network interfaces are Gigabit Ethernet ones.  Move the
Kconfig entry to the appropriate section and add some help text.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/Kconfig

@@ -481,10 +481,6 @@ config MIPS_AU1X00_ENET
 	  If you have an Alchemy Semi AU1X00 based system
 	  say Y.  Otherwise, say N.
 
-config NET_SB1250_MAC
-	tristate "SB1250 Ethernet support"
-	depends on SIBYTE_SB1xxx_SOC
-
 config SGI_IOC3_ETH
 	bool "SGI IOC3 Ethernet"
 	depends on PCI && SGI_IP27
@@ -2127,6 +2123,18 @@ config R8169_VLAN
 	  
 	  If in doubt, say Y.
 
+config NET_SB1250_MAC
+	tristate "SB1250 Gigabit Ethernet support"
+	depends on SIBYTE_SB1xxx_SOC
+	---help---
+	  This driver supports Gigabit Ethernet interfaces based on the
+	  Broadcom SiByte family of System-On-a-Chip parts.  They include
+	  the BCM1120, BCM1125, BCM1125H, BCM1250, BCM1255, BCM1280, BCM1455
+	  and BCM1480 chips.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called sb1250-mac.
+
 config SIS190
 	tristate "SiS190/SiS191 gigabit ethernet support"
 	depends on PCI