PCI ops: MMCONF_SUPPORT_DEFAULT is required

Doing PCI config operations via MMIO window by default is a
requirement, if supported by the platform. This means chipset
or CPU code must enable MMCONF operations early in bootblock
already, or before platform-specific romstage entry.

Platforms are allowed to have NO_MMCONF_SUPPORT only in the
case it is actually not implemented in the silicon.

Change-Id: Id4d9029dec2fe195f09373320de800fcdf88c15d
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/17693
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/northbridge/intel/i945/bootblock.c

@@ -9,12 +9,12 @@ static void bootblock_northbridge_init(void)
 
 	/*
 	 * The "io" variant of the config access is explicitly used to
-	 * setup the PCIEXBAR because CONFIG_MMCONF_SUPPORT_DEFAULT is set to
+	 * setup the PCIEXBAR because CONFIG_MMCONF_SUPPORT is set to
 	 * to true. That way all subsequent non-explicit config accesses use
 	 * MCFG. This code also assumes that bootblock_northbridge_init() is
 	 * the first thing called in the non-asm boot block code. The final
 	 * assumption is that no assembly code is using the
-	 * CONFIG_MMCONF_SUPPORT_DEFAULT option to do PCI config acceses.
+	 * CONFIG_MMCONF_SUPPORT option to do PCI config acceses.
 	 *
 	 * The PCIEXBAR is assumed to live in the memory mapped IO space under
 	 * 4GiB.