i2c: tegra: match return type of wait_for_completion_timeout

return type of wait_for_completion_timeout is unsigned long not int. As ret
was only used for wait_for_completion_timeout here it is renamed to time_left
the type changed to unsigned long and references fixed up.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>