PCI: qcom: Add SM8550 PCIe support

PCI: qcom: Add SM8550 PCIe support

SM8550 requires two additional clocks for proper working.

Add these two clocks as optional clocks (as only required by this
platform) and compatible for this platform.

While at it, let's also rename the reset variable to "rst" from
"pci_reset" to match the existing naming preference.

Link: https://lore.kernel.org/r/20230320144658.1794991-2-abel.vesa@linaro.org
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
[lpieralisi@kernel.org: commit log rewording]
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>