uio_mf624: Refactor memory info initialization

No functional changes. Move initialization of struct uio_mem to a
function. This will allow the next commit to change the initialization
code at a single place rather that at three different places.

Signed-off-by: Michal Sojka <sojkam1@fel.cvut.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>