remoteproc: mtk_scp: Use devm variant of rproc_alloc()

remoteproc: mtk_scp: Use devm variant of rproc_alloc()

To simplify the probe function, switch from using rproc_alloc() to
devm_rproc_alloc(); while at it, also put everything on a single line,
as it acceptably fits in 82 columns.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220124120915.41292-1-angelogioacchino.delregno@collabora.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>