staging: greybus: Add blank line after declaration

Add a blank line after a declaration. Error found by checkpatch.

Signed-off-by: Elizabeth Ferdman <gnudevliz@gmail.com>
Reviewed-by: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Reviewed-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>