firmware: tegra: set drvdata earlier

Subdevices of bpmp, such as bpmp-i2c, require the bpmp device's
drvdata to be set during their probe. Currently this is not always the
case. Fix this by calling platform_set_drvdata() earlier during bpmp's
probe.

Signed-off-by: Timo Alho <talho@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>