ARM: at91/feature-removal-schedule: delay at91_mci removal

Delay sd/mmc driver at91_mci.c removal because of tight schedule to
move platform data to new driver atmel-mci.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>