classes/binconfig: fix indentation in python function
If we don't fix this, the recently added dependency from
do_populate_sysroot on functions in SYSROOT_PREPROCESS_FUNCS in
staging.bbclass triggers warnings that the get_binconfig_mangle
function contains tabs for all recipes that inherit binconfig.
Related to fix for [YOCTO #5852].
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
