Fixes NotificationHeaderView layout.

The layout method in NotificationHeaderView was incorrectly adding the
margins, width, etc. of views laid out on the right side to the position
it was tracking for views being laid out on the left side.  This change
fixes that error.

Test: manual
Change-Id: I747b318c621e6cf518e0752020ca8909c36c2ed7
Fixes: 122036911