uboot-imx

SIMPC8313 board: fix out of tree building.

Fix typo in makefile which broke out of tree builds.

Also use expolicit "rm" instead of "ln -sf" which is known to be
unreliable.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>