Fix indenting in primary_call_info.xml.

This is to fix intentional incorrect indenting when the original change
was submitted because the indentations made it hard to do a code
comparison. This change does NOT modify functionality at all, it is
simply a +4 indent for the linear layout "primary_call_banner".

Bug: 23351559
Change-Id: I6b891c96d18e91489911e2f2d79c88e09ccc9ef5