board: ls1046a: use default scan_dev_for_boot

Default environment variable is more complete. Also scans for efi
binaries for example.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Reviewed-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
1 file changed