remoteproc/wkup_m3: Set deny_sysfs_ops flag

The Wakeup M3 remote processor is controlled by the wkup_m3_ipc
client driver, so set the newly introduced 'deny_sysfs_ops' flag
to not allow any overriding of the remoteproc firmware or state
from userspace.

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