PCI: dra7xx: PCI_EXP_LNKCTL2 usage

ab5fe4f4d31e ("PCI: dra7xx: Add support to force RC to work in GEN1 mode") added this:

+ dw_pcie_cfg_read(pp->dbi_base + exp_cap_off + PCI_EXP_LNKCTL2,
+ 2, &reg);
+ if ((reg & PCI_EXP_LNKCAP_SLS) != PCI_EXP_LNKCAP_SLS_2_5GB) {

  +               reg &= ~((u32)PCI_EXP_LNKCAP_SLS);
  +               reg |= PCI_EXP_LNKCAP_SLS_2_5GB;
  +               dw_pcie_cfg_write(pp->dbi_base + exp_cap_off +

+ PCI_EXP_LNKCTL2, 2, reg);
+ }

This probably works as intended, but it *looks* wrong because it uses LNKCAP_* symbols on LNKCTL2 register values. We do have PCI_EXP_LNKCTL2_* symbols, so I think it would be better if we used used those.

Bjorn