Fix partial HW dithered refreshes sometimes appearing to shift refreshed content (#6267)

* Fix HW dithered partial refreshes sometimes behaving as if the refreshed
content had moved a few pixels to the side...

Probably a kernel issue with the alignment fixup in the EPDC?

* Get rid of the legacy coordinates fixup

It shouldn't be necessary anymore.
And I'd rather fix the root cause, anyway.

* Bump base

(https://github.com/koreader/koreader-base/pull/1116)

* Missed a few DIVs in #6224

frontend/ui/widget/multiconfirmbox.lua

@@ -87,7 +87,7 @@ function MultiConfirmBox:init()
         TextBoxWidget:new{
             text = self.text,
             face = self.face,
-            width = Screen:getWidth()*2/3,
+            width = math.floor(Screen:getWidth() * 2/3),
         }
     }