firmware: tegra: Enable BPMP support on Tegra234

Enable support for the BPMP on Tegra234 to avoid relying on Tegra194
being enabled to pull in the needed OF device ID table entry.

On simulation platforms the BPMP hasn't booted up yet by the time we
probe the BPMP driver and the BPMP hasn't had a chance to mark the
doorbell as ringable by the CCPLEX. This corresponding check in the
BPMP driver will therefore fail. Work around this by disabling the
check on simulation platforms.

Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>