coresight: etm4x: remove redundant fields in etmv4_save_state

Some of fields are redundant in etmv4_save_state and never used:

    ss_status => trcsscsr
    seq_state => trcseqstr
    cntr_val => trccntvr
    vinst_ctrl => trcvictlr

Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20260725113645.57519-13-yeoreum.yun@arm.com