sb/intel/bd82x6x: Reduce function-disable mess

Most affected boards set the function disabled (FD) register to an
arbitrary state dumped from systems running the vendor BIOS. This
makes it impossible to enable the devices in devicetree and a pretty
big mess of course because nobody cared to keep the register in sync
with the devicetree.

To get completely rid of most of the writes to FD, move setting of
PCH_DISABLE_ALWAYS into the southbridge code where it belongs.

Change-Id: Ia2a507cbcdf218d09738e2e16f0d3ad1dcf57b8b
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/23255
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Hal Martin <hal.martin+coreboot@gmail.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Bill XIE <persmule@gmail.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/mainboard/samsung/lumpy/romstage.c b/src/mainboard/samsung/lumpy/romstage.c
index 1fde58e..131be72 100644
--- a/src/mainboard/samsung/lumpy/romstage.c
+++ b/src/mainboard/samsung/lumpy/romstage.c
@@ -63,10 +63,8 @@
 #endif
 }
 
-void rcba_config(void)
+void mainboard_rcba_config(void)
 {
-	u32 reg32;
-
 	/*
 	 *             GFX    INTA -> PIRQA (MSI)
 	 * D28IP_P1IP  WLAN   INTA -> PIRQB
@@ -107,11 +105,6 @@
 	RCBA16(OIC) = 0x0100;
 	/* PCH BWG says to read back the IOAPIC enable register */
 	(void) RCBA16(OIC);
-
-	/* Disable unused devices (board specific) */
-	reg32 = RCBA32(FD);
-	reg32 |= PCH_DISABLE_ALWAYS;
-	RCBA32(FD) = reg32;
 }
 
 static const uint8_t *locate_spd(void)