PCI: qcom: Sort and group registers and bitfield definitions

Sorting the registers and their bit definitions will make it easier to add
more definitions in the future and it also helps in maintenance.

While at it, let's also group the registers and bit definitions separately
as done in the pcie-qcom-ep driver.

Link: https://lore.kernel.org/r/20230316081117.14288-4-manivannan.sadhasivam@linaro.org


Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>