refactor(plat/nxp/lx216x): refine variable definition

This patch will make BL2_BASE to be hex valaue but
not a shell command.

Signed-off-by: Jiafei Pan <Jiafei.Pan@nxp.com>
Change-Id: Iebb86a0b9bc8cab1676bd8e898cf4a1b6d16f472
1 file changed