The fix for build type detection in librealsense's CMakeLists.txt
turned out to be non-functional in the official ROS build farm as
explained in https://github.com/IntelRealSense/librealsense/pull/404



Since this recipe is specific to meta-ros set the build type
explicitly to ROS to guaranty the catkin-related configs for
librealsense get created and installed properly.

Signed-off-by: Dmitry Rozhkov <dmitry.rozhkov@linux.intel.com>