PCI: mobiveil: Return bool from link up check

PCI: mobiveil: Return bool from link up check

PCIe link status check is supposed to return a boolean to indicate whether
the link is up or not. So update ls_g4_pcie_link_up() to return bool and
also simplify the LTSSM state check.

Signed-off-by: Hans Zhang <18255117159@163.com>
[mani: commit message rewording]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Link: https://patch.msgid.link/20250510160710.392122-3-18255117159@163.com