The current code doesn't check whether platform_get_resource_byname()
succeeded to get the l1tcm memory, which is optional, before attempting
to map it. This results in the following error message when it is
missing:
mtk-scp 10500000.scp: error -EINVAL: invalid resource (null)
Add a check so that the remapping is only attempted if the memory region
exists. This also allows to simplify the logic handling failure to
remap, since a failure then is always a failure.
Fixes: ca23ecfdbd44 ("remoteproc/mediatek: support L1TCM")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>