MAINTAINERS: Update remoteproc repo url

The remoteproc and rpmsg repos are moving from my personal namespace to
allow Mathieu to push to the projects as well.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210927210946.3746116-1-bjorn.andersson@linaro.org


Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>