SATA 3.0 actually supports an 6.0Gbps rate and I've encountered systems
out there with disks at such a speed. dsa-check-hpssacli currently warns
about them because it seems to support only up to 3.0Gbps. Add support
for an "6.0Gbps" value.
SATA 3.2 goes up to 16Gbps but I have not seen this in the wild yet, so
it's unknown how hpssacli would display such a thing. Avoid guessing for
now.
Signed-off-by: Julien Cristau <jcristau@debian.org>