This patch is identical to that introduced in
1a1276e7 to the Linus' 2.6 development tree
by Alan Cox.

'This is based on the proposed patches flying around but also checks that
the device in question is new enough to have word 93 rather thanb blindly
assuming word 93 == 0 means SATA (see ATA-5, ATA-7)' -- Alan Cox

Required for my SATA drive on an Asus Pundit-R to operate above 33MBps.
Signed-off-by: Michael-Luke Jones <mlj28@cam.ac.uk>
Signed-off-by: Adrian Bunk <bunk@stusta.de>