clk: tegra: Fix Tegra PWM parent clock

Commit 8c193f47 ("pwm: tegra: Optimize period calculation") updated
the period calculation in the Tegra PWM driver and now returns an error
if the period requested is less than minimum period supported. This is
breaking PWM support on various Tegra platforms. For example, on the
Tegra210 Jetson Nano platform this is breaking the PWM fan support and
probing the PWM fan driver now fails ...

 pwm-fan pwm-fan: Failed to configure PWM: -22
 pwm-fan: probe of pwm-fan failed with error -22

The problem is that the default parent clock for the PWM on Tegra210 is
a 32kHz clock and is unable to support the requested PWM period.

Fix PWM support on Tegra20, Tegra30, Tegra114, Tegra124 and Tegra210 by
updating the parent clock for the PWM to be the PLL_P.

Fixes: 8c193f47 ("pwm: tegra: Optimize period calculation")
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Robert Eckelmann <longnoserob@gmail.com> # TF101 T20
Tested-by: Antoni Aloy Torrens <aaloytorrens@gmail.com> # TF101 T20
Tested-by: Svyatoslav Ryhel <clamor95@gmail.com> # TF201 T30
Tested-by: Andreas Westman Dorcsak <hedmoo@yahoo.com> # TF700T T3
Link: https://lore.kernel.org/r/20221010100046.6477-1-jonathanh@nvidia.com


Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>