PCI: tegra: Use lower-case hex consistently for register definitions

Most of the register definitions use lowercase hexadecimal values, with a
few exceptions using uppercase.  Convert the latter to be more in line with
the former.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>