arm: at91: fix compiler warning for eb01 board build

Fix compiler warning when building for AT91EB01 board:

arch/arm/mach-at91/board-eb01.c:41: warning: initialisation from incompatible pointer type

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>