Reverting folder cell width on portrait phones.

The extra folder cell space added in ag/790800 looks bad on phones in
portrait mode, so reverting it here. However, we keep the extra space
on tablets or phones in landscape mode, since it provides more room
for long app names (bug 22462641).

Bug: 25662215
Change-Id: I2a37b884458ee557c9b8cff0c3edef16bfc50efb