remoteproc: Move handling of cached table to boot/shutdown

As we moved the vdev handling to the main boot/shutdown code path we can
further simplify the resource table handling by moving the parsing spet
to boot as well. The lifespan of the resource table is changed to live
from rproc_boot() to rproc_shutdown().

Cc: Lee Jones <lee.jones@linaro.org>
Cc: Loic Pallardy <loic.pallardy@st.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>