There is no mutex protection of the state checking before rproc_boot(),
which can't guarantee there is no another instance is trying to do
same operation.

Consider two instances case:
Instance1: echo start > /sys/class/remoteproc/remoteproc0/state
Instance2: echo start > /sys/class/remoteproc/remoteproc0/state
...
Instance2: echo stop > /sys/class/remoteproc/remoteproc0/state
...
Instance1: echo stop > /sys/class/remoteproc/remoteproc0/state

The one issue is that the instance2 case may success when 'start'
happens at same time as instance1, then rproc->power = 2; Or it
may fail with -BUSY, then rproc->power = 1; which is uncertain.

The another issue is for 'stop' operation, if the rproc->power = 1,
when instance2 'stop' the remoteproc the instance1 will be
impacted for it still needs the service at that time.

The reference counter rproc->power is used to manage state
changing and there is mutex protection in each operation
function for multi instance case.

So remove this state checking in rproc_cdev_write() and
state_store() for 'start' operation, just let reference
counter rproc->power to manage the behaviors.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/1648434012-16655-2-git-send-email-shengjiu.wang@nxp.comSigned-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>