remoteproc/mediatek: change MT8192 CFG register base

The correct MT8192 CFG register base is 0x20000 off.  Changes the
registers accordingly.

Fixes: fd0b6c1f ("remoteproc/mediatek: Add support for mt8192 SCP")
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20201210054109.587795-1-tzungbi@google.com


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