linux-yocto/5.0: fix systemtap for arm

linux-yocto/5.0: fix systemtap for arm

We need to enable the arm unwinder for systemtap to work out of the
box:

  root@qemuarm:~# stap --disable-cache -DSTP_NO_VERREL_CHECK ./hello.stp
  [ 1600.955262] stap_2097: loading out-of-tree module taints kernel.
  hello world

This option is useful for much more than systemtap, so it is a good
idea to have on in the base configs. It make the image slightly larger,
but has no performance impacts.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>