rsxx: Remove deprecated IRQF_DISABLED

This removes the use of the IRQF_DISABLED flag
from drivers/block/rsxx/core.c

It's a NOOP since 2.6.35 and it will be removed one day.

Signed-off-by: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Acked-by Philip Kelleher <pjk1939@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <axboe@fb.com>