meta-iotqa: fix a bug in run_as
meta-iotqa: fix a bug in run_as

run_as use {su username -c "cmd"} to run a cmd as username, but when cmd has some characters such as " and $, these character need escape for keep original meaning.

Signed-off-by: zjh <2b052533cdbcec2c486b017cd9ef932a2d35e8d0@intel.com>

daweiwu/meta-iotqa-1,ostroproject/meta-iotqa,wanghongjuan/meta-iotqa-1,wanghongjuan/meta-iotqa-1,daweiwu/meta-iotqa-1,wanghongjuan/meta-iotqa-1,ostroproject/meta-iotqa,wanghongjuan/meta-iotqa-1,ostroproject/meta-iotqa,daweiwu/meta-iotqa-1,daweiwu/meta-iotqa-1,ostroproject/meta-iotqa,daweiwu/meta-iotqa-1,wanghongjuan/meta-iotqa-1,ostroproject/meta-iotqa