PCI: qcom: Add equalization settings for 8.0 GT/s and 32.0 GT/s

Add lane equalization setting for 8.0 GT/s and 32.0 GT/s to enhance link
stability and avoid AER Correctable Errors reported on some platforms
(eg. SA8775P).

8.0 GT/s, 16.0 GT/s and 32.0 GT/s require the same equalization setting.
This setting is programmed into a group of shadow registers, which can be
switched to configure equalization for different speeds by writing 00b,
01b and 10b to `RATE_SHADOW_SEL`.

Hence, program equalization registers in a loop using link speed as index,
so that equalization setting can be programmed for 8.0 GT/s, 16.0 GT/s
and 32.0 GT/s.

Fixes: 489f14be ("arm64: dts: qcom: sa8775p: Add pcie0 and pcie1 nodes")
Co-developed-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
Signed-off-by: Ziyue Zhang <ziyue.zhang@oss.qualcomm.com>
[mani: wrapped the warning to fit 100 columns, used post-increment for loop]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Link: https://patch.msgid.link/20250904065225.1762793-2-ziyue.zhang@oss.qualcomm.com