dmaengine: dma-jz4780: Return error if not probed from DT

dmaengine: dma-jz4780: Return error if not probed from DT

BugLink: https://bugs.launchpad.net/bugs/1836802
[ Upstream commit 54f919a04cf221bc1601d1193682d4379dacacbd ]

The driver calls clk_get() with the clock name set to NULL, which means
that the driver could only work when probed from devicetree. From now
on, we explicitly require the driver to be probed from devicetree.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>