xz-native is needed to decompress the sources but DEPENDS isn't correct
for this, its needed at do_unpack time. base.bbclass already handles
this correctly so drop the unneeded dependency.
(From OE-Core rev: 38bf1002e3073fbe2766db911a70d20fad8d8842)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>