remoteproc: stm32: update error management in stm32_copro_start

The coprocessor is running as soon as the hold boot is de-asserted.

So indicate this running state and save the resource table even
if the protective assert, to avoid autonomous reboot, is failed.

This error case should never occurs.

Cc: Fabien DESSENNE <fabien.dessenne@st.com>
Cc: Arnaud POULIQUEN <arnaud.pouliquen@st.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>