ARM: at91: remove obsoleted init_consistent_dma_size()

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
CC: Nicolas Ferre <nicolas.ferre@atmel.com>
CC: Andrew Victor <linux@maxim.org.za>