Some endpoints like NVMe D3cold transition is prohibited as it
decreases the life time of the device (D3 cold is treated as power
cycle). So turning off the link during S3 can reduce life span of the NVMe.
For those endpoints adding a flag to inform the driver that APSS based
l1ss-sleep is supported. The PCIe driver will keep the link in L1ss and
turn off PCIe resources if this flag is set.
Change-Id: I3682bda297181eb9f5b63cf817b05e37b160b3ce