cmake: support QUIET argument for find_package

The CMake function `find_package()` supports the flag QUIET.
QUIET will disable informational printing within CMakes own
find_package function.

To align with CMakes find_package, this commit will honor the QUIET flag
and disable informational printing related to package lookup.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>