northbridge/intel/i440bx: Unify UDELAY selection

Instead of manually including udelay_io.c in each romstage,
select UDELAY_IO for all i440BX boards in the chipset.

Change-Id: I411191927f3fba1d0749edcf79378e8013fb195a
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: https://review.coreboot.org/13781
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/mainboard/biostar/m6tba/Kconfig

@@ -21,7 +21,6 @@ config BOARD_SPECIFIC_OPTIONS # dummy
 	select SOUTHBRIDGE_INTEL_I82371EB
 	select SUPERIO_SMSC_SMSCSUPERIO
 	select HAVE_PIRQ_TABLE
-	select UDELAY_TSC
 	select BOARD_ROMSIZE_KB_256
 
 config MAINBOARD_DIR

src/mainboard/biostar/m6tba/romstage.c

@@ -22,7 +22,6 @@
 #include <console/console.h>
 #include <southbridge/intel/i82371eb/i82371eb.h>
 #include <northbridge/intel/i440bx/raminit.h>
-#include "drivers/pc80/udelay_io.c"
 #include <delay.h>
 #include <cpu/x86/bist.h>
 #include <superio/smsc/smscsuperio/smscsuperio.h>