mhi: Fix double dma free

mhi_deinit_chan_ctxt functionthat takes care of unitializing channel
resources, including unmapping coherent MHI areas, can be called
from different path in case of controller unregistering/removal:
- From a client driver remove callback, via mhi_unprepare_channel
- From mhi_driver_remove that unitialize all channels

mhi_driver_remove()
|-> driver->remove()
| |-> mhi_unprepare_channel()
| |-> mhi_deinit_chan_ctxt()
|...
|-> mhi_deinit_chan_ctxt()

This leads to double dma freeing...

Fix that by preventing deinit for already uninitialized channel.

Link: https://lore.kernel.org/r/[e-mail]
Fixes: a7f422f2f89e ("bus: mhi: Fix channel close issue on driver remove")
Reported-by: Kalle Valo <[e-mail]>
Tested-by: Kalle Valo <[e-mail]>
Reviewed-by: Manivannan Sadhasivam <[e-mail]>
Signed-off-by: Loic Poulain <[e-mail]>
Signed-off-by: Manivannan Sadhasivam <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/bus/mhi/core/init.c

···
 	tre_ring = &mhi_chan->tre_ring;
 	chan_ctxt = &mhi_cntrl->mhi_ctxt->chan_ctxt[mhi_chan->chan];
 
+	if (!chan_ctxt->rbase) /* Already uninitialized */
+		return;
+
 	mhi_free_coherent(mhi_cntrl, tre_ring->alloc_size,
 			  tre_ring->pre_aligned, tre_ring->dma_handle);
 	vfree(buf_ring->base);