resource: ability to resize an allocated resource

Provides the ability to resize a resource that is already allocated.
This functionality is put in place to support reallocation needs of
pci resources.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>