ata: pata_octeon_cf: remove redundant val variable

Return value from DIV_ROUND_UP() directly instead
of taking this in another redundant variable.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Signed-off-by: CGEL ZTE <cgel.zte@gmail.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>