skd: Change default interrupt mode to MSI-X

Since MSI support on some motherboards is unreliable, change the
default interrupt mode from MSI to MSI-X. This patch avoids that
the following message appears sporadially in the kernel logs of
my test setup:

do_IRQ: 3.193 No irq handler for vector

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>