A handful of modules do not require mraa. Captured this in
src/CMakeLists.txt - only add mraa dependency for targets which
use:
upm_module_init(mraa ... )
or
upm_mixed_module_init(... REQUIRES mraa)
All sensors which use UPM interfaces (src/interfaces) now
explicitly add the interfaces target:
upm_module_init(interfaces ... )
or
upm_mixed_module_init(... REQUIRES interfaces)
Signed-off-by: Noel Eck <noel.eck@intel.com>