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/southbridge/intel/i82801gx/i82801gx.c

@@ -20,10 +20,6 @@
 #include "i82801gx.h"
 #include "sata.h"
 
-#if !CONFIG_MMCONF_SUPPORT_DEFAULT
-#error ICH7 requires CONFIG_MMCONF_SUPPORT_DEFAULT
-#endif
-
 void i82801gx_enable(device_t dev)
 {
 	u32 reg32;

src/southbridge/intel/i82801ix/i82801ix.c

@@ -23,10 +23,6 @@
 #include <console/console.h>
 #include "i82801ix.h"
 
-#if !CONFIG_MMCONF_SUPPORT_DEFAULT
-#error ICH9 requires CONFIG_MMCONF_SUPPORT_DEFAULT
-#endif
-
 typedef struct southbridge_intel_i82801ix_config config_t;
 
 static void i82801ix_enable_device(device_t dev)