soc/amd/common: Correct SPI FIFO size check

When checking that command and data fit in the FIFO, don't count the first
byte.  The command doesn't go through the FIFO.

TEST=confirm error (4+68>71) goes away on Mandolin
BUG=b:146225550

Change-Id: Ica2ca514deea401c9c5396913087e07a12ab3cf3
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37721
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Eric Peers <epeers@google.com>
Reviewed-by: Frans Hendriks <fhendriks@eltan.com>
Reviewed-by: Martin Roth <martinroth@google.com>

0 files changed, 0 insertions, 0 deletions