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/apps/reader/modules/readerfont.lua

@@ -154,7 +154,7 @@ function ReaderFont:onShowFontMenu()
         title = self.font_menu_title,
         item_table = self.face_table,
         width = Screen:getWidth() - 100,
-        height = Screen:getHeight() / 2,
+        height = math.floor(Screen:getHeight() * 0.5),
         single_line = true,
         perpage_custom = 8,
     }