SPI block transfers were broken in commit r759. Block
transfers are primarily used by the SD card interface so
this also broke accesses to the SD card.
SD card accesses should be fixed now. Verified by writing
config objects in the GCS and confirming that they survived
a reboot of the OP board.
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@808 ebee16cc-31ac-478f-84a7-5cbb03baadba