staging: hikey9xx: phy-hi3670-usb3.yaml: add a blank line

Add a blank line after maintainers field.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/2bd13d3e141fd8826a8e791e5c65e877c6233966.1611052729.git.mchehab+huawei@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>