It doesn't need to be changed, make it const. The string literals should
anyway be referred to as const data.

The following gets moved to rodata section:

0000000000000080 l     O .rodata	0000000000001c00 cmd_info
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>