Input: ALPS - introduce helper function for repeated commands

Several ALPS driver init sequences repeat a command three times, then
issue PSMOUSE_CMD_GETINFO to read the result.  Move this into a helper
function to simplify the code.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Tested-by: Dave Turvene <dturvene@dahetral.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>