Move the common code to live_vm_common.bbclass and remove duplicated ones.
(From OE-Core rev: 4a70cc59a0350f06d4cc48c12c3053a39191ba07)
Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>