remoteproc: stm32: Parse memory regions when attaching to M4

Split function stm32_rproc_parse_fw() in two parts, the first one
to parse the memory regions and the second one to load the
resource table.  That way parsing of the memory regions can be
done without having do deal with the resource table when attaching
to a remote processor.

Mainly based on the work published by Arnaud Pouliquen [1].

[1]. https://patchwork.kernel.org/project/linux-remoteproc/list/?series=239877



Acked-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200714200445.1427257-9-mathieu.poirier@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>