sched/topology: Extract "imb_numa_nr" calculation into a separate helper

sched/topology: Extract "imb_numa_nr" calculation into a separate helper

Subsequent changes to assign "sd->shared" from "s_data" would
necessitate finding the topmost SD_SHARE_LLC to assign shared object to.

This is very similar to the "imb_numa_nr" computation loop except that
"imb_numa_nr" cares about the first domain without the SD_SHARE_LLC flag
(immediate parent of sd_llc) whereas the "sd->shared" assignment would
require sd_llc itself.

Extract the "imb_numa_nr" calculation into a helper
adjust_numa_imbalance() and use the current loop in the
build_sched_domains() to find the sd_llc.

While at it, guard the call behind CONFIG_NUMA's status since
"imb_numa_nr" only makes sense on NUMA enabled configs with SD_NUMA
domains.

No functional changes intended.

Suggested-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://patch.msgid.link/20260312044434.1974-3-kprateek.nayak@amd.com