In future, if you do not want to import the JPEGS to Photos, but keep them for reference, you could use Image Capture to import your image files from the camera to Photos.
The column View in Image Capture lets you sort the image files by the kind and this way you can easily select only the RAW files for importing to Photos. Just click the title of the column with "Kind" to sort by the kind. And set "Import to" at the bottom of the panel to "Photos":
The screenshot below shows, how I can select the CR2 files from my Canon camera after sorting by kind in Image Capture.
