linux-phytec-ti

remoteproc: deny sysfs operations with MPM userspace loader

The remoteproc framework provides sysfs interfaces for changing
the firmware name and for starting/stopping a remote processor
through the sysfs files 'state' and 'firmware'. The Keystone
remoteproc driver also supports a custom userspace-driven load
and boot mechanism called Multi Proc Manager (MPM) through a
char device and custom ioctls supporting a userspace daemon.

The sysfs interface does conflict with the MPM state-machine and
the corresponding state variables within the keystone remoteproc
driver. So, add a check to the sysfs interface operations to fix
this by obstructing any changes to the remoteproc state-machine
when a remote processor is configured for supporting the userspace
loader/boot mechanism.

Signed-off-by: Suman Anna <s-anna@ti.com>