net: devmem: fix DMA direction on unmapping

Looks like we always unmap the DMA_BUF with DMA_FROM_DEVICE direction.
While at it unexport __net_devmem_dmabuf_binding_free(), it's internal.

Found by code inspection.

Fixes: bd61848900bf ("net: devmem: Implement TX path")
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20250801011335.2267515-1-kuba@kernel.org
Change-Id: Idc00e187552edf722a42bd5fef92572c2c0ea1f3
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit fa516c0d8bf90da9d5b168757162205aafe5d0e1)
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/116941
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Kevin Berry <kpberry@google.com>
Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
(cherry picked from commit 6a9468a78b346809721d3460ba010708af261d54)
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/118142
2 files changed