Avoid talkback speaking unnecessary information

Because No items view might occupy multiple columns on recycler view
when grid mode displayed, talkback will speak such infomation.
This will confuse user so we set span column to 1 in this case.

Fix: 141223688
Test: manual
Test: atest DocumentsUIGoogleTests
Change-Id: Idfe71830cc2fb2062da1c67cf26641083f35040c