ARM: tegra: Provide PCIEXCLK reset ID

This reset is required for PCIe and the corresponding ID therefore needs
to be defined. The enumeration value for this was properly defined on
some SoCs but not on others. Similarly, some contained it in the mapping
of peripheral IDs to clock IDs, other didn't. This patch defines it
consistently for all supported SoC generations.

Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>