devfreq_cooling: make the structs devfreq_cooling_xxx visible for all

Currently the protection #ifdef CONFIG_DEVFREQ_THERMAL cuts the needed
structures devfreq_cooling_ops and devfreq_cooling_device.
The functions which are supposed to provide the empty implementation complain
about unknown structures.
Similar solution is present in include/linux/devfreq.h.

Change-Id: Iacf42ca76fe63ca8758ca62e4a93b974f2b15cd1
Reviewed-by: Ørjan Eide <orjan.eide@arm.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Git-commit: 1cea4e7776b7e9096b696eeb66364f51a8d321ec
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Felix Xiong <xayang@codeaurora.org>
Signed-off-by: Venkateswara Rao Tadikonda <vtadik@codeaurora.org>
Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>