mmc: sdhci-pci: add support of O2Micro/BayHubTech SD hosts

Add O2Micro/BayHubTech SD Host DeviceId 8520 support.
Add O2Micro/BayHubTech SD Host DeviceId 8420 & 8421 support.
Add O2Micro/BayHubTech SD Host DeviceId 8620 & 8621 support.

These card readers are used in laptops like Lenovo ThinkPad W540,
Dell Latitude E5440, Dell Latitude E6540.

Signed-off-by: Peter Guo <peter.guo@bayhubtech.com>
Signed-off-by: Adam Lee <adam.lee@canonical.com>
Signed-off-by: Chris Ball <chris@printf.net>