ata: libata: fix parameter type of ata_deadline()

ata_deadline() passes its 'unsigned long timeout_msecs'  parameter verbatim
to msecs_to_jiffies() which takes just 'unsigned int' -- eliminate unneeded
implicit cast...

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>