ab8500-charger: Run detect workaround only on AB8500

Only AB8500 has this hardware bug, so these works only need to be run
there.

Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Marcus COOPER <marcus.xm.cooper@stericsson.com>
Reviewed-by: Martin SJOBLOM <martin.w.sjoblom@stericsson.com>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>