Update environment variable by updating:
 _ BOOT_TARGET_DEVICE
 _ CONFIGS_BOOTARGS
 _ kernel_addr_r, fdtfile, fdt_addr_r, scriptaddr, fdt_high, intird_high

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>