Tegra: spe: uninit console on a timeout

Tegra: spe: uninit console on a timeout

There are chances a denial-of-service attack, if an attacker
removes the SPE firmware from the system. The console driver
would end up waiting for the firmware to respond indefinitely.
The console driver must detect such scenarios and uninit the
interface as a result.

This patch adds a timeout to the interaction with the SPE
firmware and uninits the interface if it times out.

Change-Id: I06f27a858baed25711d41105b4110865f1a01727
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>