drm/tegra: Correct idr_alloc() minimum id

drm/tegra: Correct idr_alloc() minimum id

The client ID 0 is reserved by the host1x/cdma to mark the timeout timer
work as already been scheduled and context ID is used as the clients one.
This fixes spurious CDMA timeouts.

Fixes: bdd2f9cd10eb ("drm/tegra: Don't leak kernel pointer to userspace")
Signed-off-by: Dmitry Osipenko <[email protected]>
Reviewed-by: Mikko Perttunen <[email protected]>
Signed-off-by: Thierry Reding <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/9c19a44219acd988e678cf9abe21363911184625.1497480754.git.digetx@gmail.com