skd: Remove superfluous initializations from skd_isr_completion_posted()

The value of skcmp, cmp_cntxt etc. is overwritten during every
loop iteration and is not used after the loop has finished. Hence
initializing these variables outside the loop is not necessary.
This patch does not change any functionality.

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>