early_res: Add free_early_partial()

To free partial areas in pcpu_setup...

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
LKML-Reference: <4B85E245.5030001@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>