sb/amd/sb700: Add option to increase SPI speed to 33MHz

Some SB700-based systems and ROMs support high speed (33MHz) SPI
access instead of the power-on default 16.5MHz.  Add an option
to enable high speed SPI access in the bootblock, and set the
default value to Disabled.  This greatly decreases boot time on
SB700-based systems, especiall when a large payload is in use.

On a KGPE-D16 with a Petitboot (Linux + initramfs) payload, the
command prompt was accessible within 20 seconds of power on, which
incidentally is faster than the proprietary BIOS on the same machine
could even reach the GRUB bootloader.

Change-Id: Iadbd9bb611754262ef75a5e5a6ee4390a46e45cf
Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>
Test: Booted KGPE-D16 with Linux payload
Reviewed-on: https://review.coreboot.org/16306
Tested-by: build bot (Jenkins)
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Martin Roth <martinroth@google.com>

0 files changed, 0 insertions, 0 deletions