cpu/intel: Rename socket_mFCPGA478 to socket_m

The name was wrong. mFCPGA478 is actually a pseudonym for mPGA478MN,
the successor of the socket that was meant.

The official name of this socket is mPGA478MT. But "Socket M" is much
easier to distinguish.

Change-Id: I4efeaca69acddfcdc5e957b0b521544314d46eeb
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/c/31642
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

src/mainboard/getac/p470/Kconfig

@@ -17,7 +17,7 @@ if BOARD_GETAC_P470
 config BOARD_SPECIFIC_OPTIONS
 	def_bool y
 	select SYSTEM_TYPE_LAPTOP
-	select CPU_INTEL_SOCKET_MFCPGA478
+	select CPU_INTEL_SOCKET_M
 	select NORTHBRIDGE_INTEL_I945
 	select NORTHBRIDGE_INTEL_SUBTYPE_I945GM
 	select SOUTHBRIDGE_INTEL_I82801GX

src/mainboard/getac/p470/devicetree.cb

@@ -20,7 +20,7 @@ chip northbridge/intel/i945
 	register "gfx.did" = "{ 0x80000100, 0x80000410, 0x80000320, 0x80000410, 0x00000005 }"
 
         device cpu_cluster 0 on
-                chip cpu/intel/socket_mFCPGA478
+                chip cpu/intel/socket_m
                         device lapic 0 on end
                 end
         end