Update it to 4.20-rc1

Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Message-Id: <f9346f1816b940a4231524a84d57a2cac8466ccc.1549555521.git.yi.z.zhang@linux.intel.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>