drive: Remove unused DriveServiceInterface::TouchResource

UpdateResource can do the same thing.

BUG=None
TEST=build

Review URL: https://codereview.chromium.org/100903005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238387 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238387