ARM: DRA7/OMAP5: Enable ACTLR[0] (Enable invalidates of BTB) for secondary cores

Call secure services to enable ACTLR[0] (Enable invalidates of BTB with
ICIALLU) when branch hardening is enabled for kernel.

On GP devices OMAP5/DRA7, there is no possibility to update secure
side since "secure world" is ROM and there are no override mechanisms
possible. On HS devices, appropriate PPA should do the workarounds as
well.

However, the configuration is only done for secondary core, since it is
expected that firmware/bootloader will have enabled the required
configuration for the primary boot core (note: bootloaders typically
will NOT enable secondary processors, since it has no need to do so).

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>