sb/intel/bd82x6x: Make the pch_enable_lpc hook optional

This also changes the name to mainboard_pch_lpc_setup to better
reflect that it is an optional mainboard hook.

This adds an empty weakly linked default. The rationale behind this
change is that without an implementation of the hook some features
might not work but that the result is likely still able to boot, so it
can be made optional.

Change-Id: Ie8e6056b4c4aed3739d2d12b4224de36fe217189
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36782
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/src/mainboard/sapphire/pureplatinumh61/romstage.c b/src/mainboard/sapphire/pureplatinumh61/romstage.c
index 3c9cc82..bc08fd8 100644
--- a/src/mainboard/sapphire/pureplatinumh61/romstage.c
+++ b/src/mainboard/sapphire/pureplatinumh61/romstage.c
@@ -21,7 +21,7 @@
 #include <northbridge/intel/sandybridge/raminit_native.h>
 #include <southbridge/intel/bd82x6x/pch.h>
 
-void pch_enable_lpc(void)
+void mainboard_pch_lpc_setup(void)
 {
 	pci_write_config32(PCI_DEV(0, 0x1f, 0), 0xac, 0x00010000);
 }