cpuidle: tegra: Fix C7 idling state on Tegra114

Trusted Foundation firmware doesn't implement the do_idle call and in
this case suspending should fall back to the common suspend path. In order
to fix this issue we will unconditionally set the NOFLUSH_L2 mode via
firmware call, which is a NO-OP on Tegra30/124, and then proceed to the
C7 idling, like it was done by the older Tegra114 cpuidle driver.

Fixes: 14e086ba ("cpuidle: tegra: Squash Tegra114 driver into the common driver")
Cc: stable@vger.kernel.org # 5.7+
Reported-by: Anton Bambura <jenneron@protonmail.com> # TF701 T114
Tested-by: Anton Bambura <jenneron@protonmail.com> # TF701 T114
Tested-by: Matt Merhar <mattmerhar@protonmail.com> # Ouya T30
Tested-by: Peter Geis <pgwipeout@gmail.com> # Ouya T30
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210302095405.28453-1-digetx@gmail.com