dmaengine: dw-edma: Program endpoint function numbers

The eDMA/HDMA transfers the driver issues carry a requester function
number in their TLPs, but nothing ever programs it: eDMA v0 leaves the
FUNC_NUM field of the channel control word zero and HDMA leaves the
per-channel func_num register at its reset value, so every transfer is
attributed to function 0. That is invisible in single-function setups,
but once the DMA block serves a non-zero endpoint function, its
requests must carry that function's number for the host to attribute
and translate them correctly.

Record the function number in the chip data (PCI_FUNC() of the probing
device for dw-edma-pcie) and program it per channel.

Endpoint-local chip instances keep func_no at 0, so transfers issued by
the endpoint-side driver remain PF0-attributed. Delegated channels are
programmed by the host-side dw-edma-pcie instance when it takes over the
channel, using that instance's PCI_FUNC().

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Link: https://patch.msgid.link/20260721062815.4117887-15-den@valinux.co.jp
Signed-off-by: Vinod Koul <vkoul@kernel.org>