drivers/perf: arm-cmn: Add space after ','

Fix a warning from checkpatch.pl.

ERROR: space required after that ',' (ctx:VxV)

Signed-off-by: Junhao He <hejunhao2@hisilicon.com>
Signed-off-by: Jay Fang <f.fangjian@huawei.com>
Link: https://lore.kernel.org/r/1620736054-58412-4-git-send-email-f.fangjian@huawei.com


Signed-off-by: Will Deacon <will@kernel.org>