package/amd-catalyst: Add support AMD CCCLE

package/amd-catalyst: Add support AMD CCCLE

The AMD Catalyst Linux driver includes a graphical controler center for AMD
graphics accelerators, called Catalyst Controler Center. This commits
adds support to install this tool by adding a separated prompt.

Signed-off-by: Romain Perier <romain.perier@free-electrons.com>
[Thomas:
 - As noticed by Yann, fixed the dependency of the comment related to
   the Qt PNG functionality.
 - Also add the Qt PNG dependency to the BR2_PACKAGE_AMD_CATALYST_CCCLE
   option itself, noticed by Yann.
 - Add an empty line, also noticed by Yann.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>