remoteproc: Fix IDR initialisation in rproc_alloc()

remoteproc: Fix IDR initialisation in rproc_alloc()

If ida_simple_get() returns an error when called in rproc_alloc(),
put_device() is called to clean things up.  By this time the rproc
device type has been assigned, with rproc_type_release() as the
release function.

The first thing rproc_type_release() does is call:
    idr_destroy(&rproc->notifyids);

But at the time the ida_simple_get() call is made, the notifyids
field in the remoteproc structure has not been initialized.

I'm not actually sure this case causes an observable problem, but
it's incorrect.  Fix this by initializing the notifyids field before
calling ida_simple_get() in rproc_alloc().

Fixes: b5ab5e24e960 ("remoteproc: maintain a generic child device for each rproc")
Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suman Anna <s-anna@ti.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20200415204858.2448-2-mathieu.poirier@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>