coresight: cti: Fix DT filter signals silently ignored

coresight: cti: Fix DT filter signals silently ignored

In cti_plat_process_filter_sigs(), after allocating a temporary
cti_trig_grp struct via kzalloc_obj(), the code never assigns tg->nr_sigs
= nr_filter_sigs. Since kzalloc zero-initialises the struct, tg->nr_sigs
remains 0. cti_plat_read_trig_group() guards with:
    if (!tgrp->nr_sigs)
        return 0;

so it returns immediately without reading any signal indices from DT.

Fix by assigning tg->nr_sigs before calling cti_plat_read_trig_group().

Fixes: a5614770ab97 ("coresight: cti: Add device tree support for custom CTI")
Signed-off-by: Yingchao Deng <yingchao.deng@oss.qualcomm.com>
Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20260426-nr_sigs-v1-1-3b9df99dab97@oss.qualcomm.com