i965/gen9: Don't use encrypted MOCS

i965/gen9: Don't use encrypted MOCS

On gen9+ MOCS is an index into a table. It is 7 bits, and AFAICT, bit 0 is for
doing encrypted reads.

I don't recall how I decided to do this for BXT. I don't know this patch was
ever needed, since it seems nothing is broken today on SKL. Furthermore, this
patch may no longer be needed because of the ongoing changes with MOCS setup. It
is what is being used/tested, so it's included in the series.

The chosen values are the old values left shifted. That was also an arbitrary
choice.

v2: Use shift in MOCS to make it clear what we're doing. (Ken)

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>