MAINTAINERS: Add linux-phy list and patchwork

Linux-phy subsystem gained mailing list and a patchwork instance. Add the
details to MAINTAINERS file

Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20210226111233.2601369-1-vkoul@kernel.org


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