[PATCH] libata: PHY reset requires writing 0x4 to SControl

Hi,

Reading the Intel VSC and AHCI it seems like writing 0x302 is incorrect.
The only valid values are 4, 1 and 0.  Writing 4 disables the
PHY.

Signed-off-by: Martin Hicks <mort@bork.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>