remoteproc: fix trace buffer va initialization

With rproc_alloc_registered_carveouts() introduction, carveouts are
allocated after resource table parsing.
rproc_da_to_va() may return NULL at trace resource registering.
This patch modifies trace debufs registering to provide device address
(da) instead of va.
da to va translation is done at each trace buffer access
through debugfs interface.

Fixes: d7c51706 ("remoteproc: add alloc ops in rproc_mem_entry struct")

Signed-off-by: Loic Pallardy <loic.pallardy@st.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>