HSD# 18022969776: firmware: stratix10-rsu: prevent io block when sending RSU messages

commit d615fc0464b09035bca7a306112bb5767328515d from
https://github.com/altera-opensource/linux-socfpga.git

 socfpga-6.1.55-lts.

Fix the issue for preventing recursive rsu mutex lock
issue in RSU update command.

Signed-off-by: Kah Jing Lee <kah.jing.lee@intel.com>
Signed-off-by: Liwei Song <liwei.song@windriver.com>