arm64: dts: sdm845-db845c: make firmware filenames follow linux-firmware

Cange aDSP and cDSP firmware filenames to follow filenames merged into
linux-firmware tree. Switch from split .mdt files to merged .mbn files.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20210318201405.2244723-1-dmitry.baryshkov@linaro.org


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