Add 'lr_svc' as a boot parameter in AArch32 bl1. This is used by Optee
and Trusty to get the non-secure entry point on AArch32 platforms.

This change is not ported in AArch64 mode where the BL31, not BL32,
is in charge of booting the non secure image (BL33).
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>