The newly introduced ahci_platform_shutdown() method is called during
system shutdown to disable host controller DMA and interrupts in order
to avoid potentially corrupting or otherwise interfering with a new
kernel being started with kexec.
Signed-off-by: NNate Watterson <nwatters@codeaurora.org>
Signed-off-by: NTejun Heo <tj@kernel.org>