drm/nouveau/i2c/g94-: increase NV_PMGR_DP_AUXCTL_TRANSACTREQ timeout

[ Upstream commit 0156e76d

 ]

Tegra TRM says worst-case reply time is 1216us, and this should fix some
spurious timeouts that have been popping up.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>