trusted-firmware-a: install/deploy multiple variants of the target

Installing and deploying .bin and .elf shouldn't be mutually exclusive.
There are scenarios where both can be useful - .bin for booting and .elf
for debugging.

Signed-off-by: Denys Dmytriyenko <denys@ti.com>
Reviewed-by: Diego Sueiro <diego.sueiro@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>