x86: remove Intel MPX

From: Dave Hansen <dave.hansen@linux.intel.com>

MPX requires recompiling applications, which requires compiler suppport.
Unfortunately, GCC 9.1 is expected to be be released without support for
MPX.  This means that there was only a relatively small window where
folks could have ever used MPX.  It failed to gain wide adoption in the
industry, and Linux was the only mainstream OS to ever support it widely.

Support for the feature may also disappear on future processors.

The benefits of keeping the feature in the tree is not worth the ongoing
maintenance cost.

It was a fun run, but it's time for it to go.  Adios, MPX!

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
36 files changed