st2205: make pointer const like the value copied to it
st2205: make pointer const like the value copied to it

Fixes a compiler warning, by doing what appears to he the
right thing.

gphoto/libgphoto2,gphoto/libgphoto2,gphoto/libgphoto2,gphoto/libgphoto2,gphoto/libgphoto2,gphoto/libgphoto2