media: staging: rkisp1: stats: replace spin_lock_irqsave with spin_lock_irq

The function 'rkisp1_stats_vb2_stop_streaming' runs in user context
therefore it is enough to use spin_lock_irq

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Acked-by: Helen Koike <helen.koike@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>