firmware: tegra: bpmp: Fix Tegra234-only builds

[ Upstream commit bd778b893963d67d7eb01f49d84ffcd3eaf229dd ]

The tegra186_bpmp_ops symbol is used on Tegra234, so make sure it's
available.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>