PCI: dwc: Use msleep() in dw_pcie_wait_for_link()

According to [1], msleep should be used for large sleeps, such as the
100-ish ms one in this function. Comply with the guide and use it.

[1] https://docs.kernel.org/timers/timers-howto.html

[kwilczynski: commit log]
Link: https://lore.kernel.org/linux-pci/20240215-topic-pci_sleep-v2-1-79334884546b@linaro.org


Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>