kernel: Only build bcc/perf on x86 and latest stable and LTS
kernel: Only build bcc/perf on x86 and latest stable and LTS

This was previously build for 5.4 and 4.19. Latest LTS is 5.4 and
latest stable is 5.6. Also skip s390x build for perf

Signed-off-by: Rolf Neugebauer <bc755ac45a0e799d1d490cba76febc56d80cc5fc@rneugeba.io>

konstruktoid/linuxkit,deitch/linuxkit,JohnnyLeone/linuxkit,justincormack/linuxkit,furious-luke/linuxkit,JohnnyLeone/linuxkit,linuxkit/linuxkit,rn/linuxkit,rn/linuxkit,furious-luke/linuxkit,konstruktoid/linuxkit,deitch/linuxkit,deitch/linuxkit,djs55/linuxkit,furious-luke/linuxkit,linuxkit/linuxkit,linuxkit/linuxkit,linuxkit/linuxkit,JohnnyLeone/linuxkit,djs55/linuxkit,justincormack/linuxkit,linuxkit/linuxkit,djs55/linuxkit,deitch/linuxkit,justincormack/linuxkit,rn/linuxkit,deitch/linuxkit,konstruktoid/linuxkit,djs55/linuxkit,djs55/linuxkit,rn/linuxkit,justincormack/linuxkit,furious-luke/linuxkit,furious-luke/linuxkit,JohnnyLeone/linuxkit,konstruktoid/linuxkit,justincormack/linuxkit,konstruktoid/linuxkit,konstruktoid/linuxkit,JohnnyLeone/linuxkit,justincormack/linuxkit,rn/linuxkit