Impact: configuration bug fix

Just like for x86-64, the range of widths valid for NODE_SHIFT is not
unbounded. The upper bound 64-bit uses is definitely also an upper
bound for 32-bit.
Signed-off-by: NJan Beulich <jbeulich@novell.com>
LKML-Reference: <49B90F12.76E4.0078.0@novell.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>