x86/platform/UV/NMI: Fix uneccessary kABI breakage

The addition of support for UV Hubless systems unneccessarily broke
the kABI for a symbol that is not used by external kernel modules.
Remove the symbol from the EXPORT list.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Reviewed-by: Russ Anderson <russ.anderson@hpe.com>
Link: http://lkml.kernel.org/r/20170215001129.068078379@asylum.americas.sgi.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>