Remove unused custom attribute maxWidth from BoundedLinearLayout

Bug: none
Change-Id: I0f8e0c81f64f0c340b95374296d85800c4197c07
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1986236Reviewed-by: Theresa  <twellington@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#728226}

components/browser_ui/widget/android/java/res/values/attrs.xml

@@ -5,7 +5,6 @@
 
 <resources>
     <declare-styleable name="BoundedView">
-        <attr name="maxWidth" format="dimension" />
         <attr name="maxWidthLandscape" format="dimension" />
         <attr name="maxWidthPortrait" format="dimension" />
         <attr name="maxHeight" format="dimension" />