Commit 803739d25c2343da6d2f95eebdcbc08bf67097d4 ("[libata] replace
sata_settings with devslp_timing"), which was also Cc: stable, used a
stack buffer to receive data from ata_read_log_page(), which triggers
the following warning:
ahci 0000:00:1f.2: DMA-API: device driver maps memory fromstack [addr=ffff880140469948]
Fix this by using ap->sector_buf instead of a stack buffer.