Comment 4 for bug 1359507

[IMPACT]
The link down issue in first attempt happens due to 2 H/W errata below:

1. Due to HW errata, during speed negotiation, sometimes controller
is not able to detect ALIGN at GEN3(6Gbps) within 54.6us results in
a timeout. This issue can be recovered by issuing a COMRESET again.

2. Due to HW errata, although ALIGH detection is successfull, due to
8b/10b and disparity BERR, sometimes the signature from the drive is
not received successfully by the Host controller. Due to this the
communication with the host and drive is not established due to
locking of CDR(clock and data recovery) circuit. This issue can be
recovered by issuing a COMRESET again.

This patch fixes the above issues by retrying the COMRESET with a
maximum attempts of 3.

[TEST CASE]
Repeatedly reboot the system.

[Regression Potential]
Fix specific to the xgene ahci driver hardreset function.