fix SCHEMATICS

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
fix port mappings

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Remap SS from PB0 to PB4

For whatever reason Leostick strangely maps SS to an LED. Hence
we must use another pin, in this case pin 28. This is pin 9 on
the M14 header.

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>