mach-snapdragon: dynamic load addresses

mach-snapdragon: dynamic load addresses

Heavily inspired by Apple board code. Use the LMB allocator to configure
load addresses at runtime, and implement a lookup table for selecting a
devicetree.

As some Qualcomm RBx boards have different RAM capacities and base
addresses, it isn't possible to hardcode these regions.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Tested-by: Sumit Garg <sumit.garg@linaro.org> #qcs404
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>