qapi/ui: Fix documentation of upper bound value in InputMoveEvent

The upper bound of pointer position in InputMoveEvent should be 0x7fff,
according to INPUT_EVENT_ABS_MAX.

Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Message-ID: <20250116104433.12114-1-zhangboyang.id@gmail.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
[Phrasing tweak squashed in]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

qapi/ui.json

@@ -1133,7 +1133,7 @@
 # @axis: Which axis is referenced by @value.
 #
 # @value: Pointer position.  For absolute coordinates the valid range
-#     is 0 -> 0x7ffff
+#     is 0 to 0x7fff.
 #
 # Since: 2.0
 ##