imx: mx6: hab : Remove the cache issue workaroud in hab for i.MX6QP

Since the i.MX6QP has fixed the issue in boot ROM, so remove the workaround
for i.MX6QP.

Signed-off-by: Ye.Li <B37916@freescale.com>
Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Acked-by: Stefano Babic <sbabic@denx.de>