build: add a seperate make command for cleaning olm files
build: add a seperate make command for cleaning olm files

Currently olm will be removed as part of clean command, but it cleans up
all the dependent modules as well
Signed-off-by: Jiffin Tony Thottan <ac134a614b50f2e879db85acb9f4b45b24a210dc@gmail.com>

rook/nfs,rook/rook,rook/rook,rook/nfs,rook/nfs,rook/rook,rook/rook,rook/rook