SPI: Split writes using spi_crop_chunk()

SPI controllers in Intel and AMD bridges have a slightly different
restriction on how long transactions they can handle.

Change-Id: I3d149d4b7e7e9633482a153d5e380a86c553d871
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/6163
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
13 files changed