Correct SPL use of IMX8MN_BEACON_2GB_LPDDR

This converts 1 usage of this option to the non-SPL form, since there is
no SPL_IMX8MN_BEACON_2GB_LPDDR defined in Kconfig

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Adam Ford <aford173@gmail.com>
1 file changed