msm: mhi_dev: Add UCI support if client req > TRE length

Consider the following issue scenario:
1. Received client write request with size greater than single TRE
element length.
2. mhi_dev_write() is called from UCI layer to handle the request.
3. In mhi_dev_write(), packet is split into multiple packets of TRE
length and is expected to send as multiple packets of TRE length in
loop.
4. The first transfer with TRE length is initiated and MHI received a
completion call back as well.
5. As part of call back, UCI completion callback is called and the
client buffer is cleared.
6. As remaining transfers are not completed, seeing NULL pointer
dereference error while trying to process next transfers in the same
write request.

To handle this scenario from UCI layer, added the support to split the
packets into TRE length if the request size is greater than TRE length.
For this, saving and passing the minimum TRE size to UCI layer as part
of channel doorbell processing.

Change-Id: Id7468967e59effab690dacab6eca02d0f3f8ca2c
Signed-off-by: Sai Chaitanya Kaveti <quic_skaveti@quicinc.com>