UPSTREAM: ath10k: add hif start/stop methods for wcn3990 snoc layer

Add hif start/stop callback for allocating/freeing buffers
on tx/rx pipe and enabling/disabling the tx/rx pipe
interrupts.

Signed-off-by: Govind Singh <govinds@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Git-commit: a6e149a9ff03e00b0a4293c0cc70b37db48fdf80
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git


Change-Id: Ia2825dbbe59932b5e7e6187368187d856f7be296
Signed-off-by: Dundi Raviteja <dundi@codeaurora.org>