arm: Allow lr to be saved by board code

arm: Allow lr to be saved by board code

The link register value can be required on some boards (e.g. FEL mode on
sunxi) so use a branch instruction to jump to save_boot_params() instead
of a branch link.

This requires a branch back to save_boot_params_ret so adjust the users
to deal with this. For exynos just drop the function since it doesn't
do anything.

Signed-off-by: Simon Glass <[email protected]>
Acked-by: Siarhei Siamashka <[email protected]>
Acked-by: Hans de Goede <[email protected]>
Signed-off-by: Hans de Goede <[email protected]>