m15w blacklist overgrew by attributing unrelated problems to m15w
including R_ERR on DMA activate FIS errata.  This patch shrinks
sata_sil m15w blacklist such that it's as reported by Silicon Image.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Carlos Pardo <Carlos.Pardo@siliconimage.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>