CHG: replaced disk io for SPI

Replaced disk io with SD/SPI for avr. Future commit will adapth SPI device

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
ADD: added makefile. added spi frontend

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
CHG: preliminary SPI diskio interface

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
ADD: added .gitignore fos FatFs submodule

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
CHG: fixed spi configuration

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
CHG: Fix select/deselect behaviour and use

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
CHG: Added original delay function

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
CHG: fixed ST Lib

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
CHG: fixed spi configuration

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
FIX: fixed release_spi and rcvr_spi_buf

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
CHG: changed wait_ready delay

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
CHG: remvoed long delay in wait_ready

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
CHG: recoded all timing routine

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
FIX: fixed rcvr_datablock

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
FIX: wait_ready with new timers

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>
CHG: configure FS readonly to save flash space

Signed-off-by: Giuseppe Monteleone <info@ing-monteleone.com>