devres: Add devm_get_free_pages API

devm_get_free_pages() and devm_free_pages() are the managed counterparts
for __get_free_pages() and free_pages().

Change-Id: I342c30e10c0e379c7642acfcdb7da0470ea7f4f3
Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: 43339bed7010da6e7cf797db3216a136a974a0cd
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>