kernel-yocto/poky-default-revisions: Ensure SRCREV_machine is set for the kernels

If we don't do this and try to bring up a new machine we can trigger network
access to resolve the branch name to a revision which is undesireable.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/kernel-yocto.bbclass

@@ -46,7 +46,6 @@ python __anonymous () {
         if mach == "UNDEFINED":
             bb.data.setVar('KMACHINE_' + bb.data.expand("${MACHINE}",d), bb.data.expand("${MACHINE}",d), d)
             bb.data.setVar("KBRANCH", "yocto/standard/base", d)
-            bb.data.setVar("SRCREV_machine", "yocto/standard/base", d)
             bb.data.setVar("BOOTSTRAP", "yocto/standard/" + bb.data.expand("${MACHINE}",d), d)
 }