Input: switch to input_abs_*() access functions

Change all call sites in drivers/input to not access the ABS axis
information directly anymore. Make them use the access helpers instead.

Also use input_set_abs_params() when possible.
Did some code refactoring as I was on it.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/input.c b/drivers/input/input.c
index e1243b4..7259adb 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -204,8 +204,8 @@
 	}
 
 	/* Flush pending "slot" event */
-	if (is_mt_event && dev->slot != dev->abs[ABS_MT_SLOT]) {
-		dev->abs[ABS_MT_SLOT] = dev->slot;
+	if (is_mt_event && dev->slot != input_abs_get_val(dev, ABS_MT_SLOT)) {
+		input_abs_set_val(dev, ABS_MT_SLOT, dev->slot);
 		input_pass_event(dev, EV_ABS, ABS_MT_SLOT, dev->slot);
 	}