x86, UV: Rename hubmask to pnmask

Rename 'bau_targ_hubmask' to 'pnmask' for clarity.

The BAU distribution bit mask is indexed by pnode number, not hub or
blade number.  This important fact is not clear while the mask is
called a 'hubmask'.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Link: http://lkml.kernel.org/r/20110621122242.630995969@sgi.com


Signed-off-by: Ingo Molnar <mingo@elte.hu>