dm clone: replace spin_lock_irqsave with spin_lock_irq

dm clone: replace spin_lock_irqsave with spin_lock_irq

[ Upstream commit 6ca43ed8376a51afec790dd484a51804ade4352a ]

If we are in a place where it is known that interrupts are enabled,
functions spin_lock_irq/spin_unlock_irq should be used instead of
spin_lock_irqsave/spin_unlock_irqrestore.

spin_lock_irq and spin_unlock_irq are faster because they don't need to
push and pop the flags register.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>