Convert to new probing mechanism and add hotplug support by enabling
SATA IRQ for SError.N, marking ehi for hotplug and scheduling EH on
SATA IRQs.

Sil3112/3512/3114 family of controllers use COMRESET as TF clearing
point and can reliably wait for D2H FIS after COMRESET whether the FIS
is the first D2H FIS after POR or in response to the COMRESET.  Thus,
setting ATA_FLAG_HRST_TO_RESUME is enough for device detection after
hotplug.
Signed-off-by: Tejun Heo <htejun@gmail.com>