Fix add_source_tree if the destination directory exists

If "$source_tree/$module-$module_version" already exists when
add_source_tree is called, the cp command needs to be aware of this so
it only copies the contents of "$from" and not the containing directory
as well.

This may occur if the tarball passed to ldtarball happens to be stored
in /usr/src/$module-$module_version/

By always creating the destination directory, the cp command can assume
it is always present, and succeed whether or not the destination
directory was already present.

Signed-off-by: Jim Ramsay <jim_ramsay@dell.com>

dkms

@@ -3049,7 +3049,8 @@ add_source_tree() {
 	"$dkms_tree/$module/$version/source") return;;
 	"$dkms_tree/$module/$version/build") return;;
     esac
-    cp -fr "$from" "$source_tree/$module-$module_version"
+    mkdir -p "$source_tree/$module-$module_version"
+    cp -fr "$from"/* "$source_tree/$module-$module_version"
 }
 
 make_kmp()