staging: unisys: visornic: Update the description of 'poll_for_irq()'

staging: unisys: visornic: Update the description of 'poll_for_irq()'

Commit e99e88a9d2b06 ("treewide: setup_timer() -> timer_setup()") has
updated the parameters of 'poll_for_irq()' but not the comment above the
function.

Update the comment and fix a typo.
s/visronic/visornic/

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-By: Enrico Weigelt <info@metux.net>
Link: https://lore.kernel.org/r/20190721170824.3412-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>