Intel northbridge I945: Apply un-written naming rules

Use NORTHBRIDGE_INTEL_I945 to select the driver directory for build.

Use _SUBTYPE_945GC and _SUBTYPE_945GM to define at compile-time
which model of I945 the driver is built for.

Change-Id: I11b1e0998d0fc28f8946bad4f0989036a9b18af4
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/684
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
diff --git a/src/mainboard/lenovo/x60/Kconfig b/src/mainboard/lenovo/x60/Kconfig
index 69f83a8..3fdfe2f 100644
--- a/src/mainboard/lenovo/x60/Kconfig
+++ b/src/mainboard/lenovo/x60/Kconfig
@@ -4,7 +4,8 @@
 	def_bool y
 	select ARCH_X86
 	select CPU_INTEL_SOCKET_MFCPGA478
-	select NORTHBRIDGE_INTEL_I945GM
+	select NORTHBRIDGE_INTEL_I945
+	select NORTHBRIDGE_INTEL_SUBTYPE_I945GM
 	select SOUTHBRIDGE_INTEL_I82801GX
 	select SOUTHBRIDGE_RICOH_RL5C476
 	select SUPERIO_NSC_PC87382