remoteproc: mtk_scp: Fix a potential double free

remoteproc: mtk_scp: Fix a potential double free

'scp->rproc' is allocated using devm_rproc_alloc(), so there is no need
to free it explicitly in the remove function.

Fixes: c1407ac1099a ("remoteproc: mtk_scp: Use devm variant of rproc_alloc()")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/1d15023b4afb94591435c48482fe1276411b9a07.1648981531.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>