soc/tegra: pmc: Use the new reset APIs to manage reset controllers

Make use of of_reset_control_array_get_exclusive() to manage
an array of reset controllers available with the device.

Cc: Jon Hunter <jonathanh@nvidia.com>
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
[p.zabel@pengutronix.de: switch to hidden reset control array]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>