Revert "AHCI: Optimize single IRQ interrupt processing"

This reverts commit 18dcf433.
IRQF_ONESHOT was missing from the conversion causing screaming
interrupts problems on some setups and LKP detected measureable drop
in IO performance.  It looks like we'll first need to drop the
threaded IRQ handling first before splitting locking.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Gordeev <agordeev@redhat.com>
Reported-by: kernel test robot <fengguang.wu@intel.com>
Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/g/20141027021651.GF27038@yliu-dev.sh.intel.com
Link: http://lkml.kernel.org/g/1414082970-20775-1-git-send-email-marc.zyngier@arm.com