ata: pata_ali: remove redundant return statement

A return statement is unnecessarily complicated, currently value
in variable mask is bitwise-masked and the variable is being
updated and then returned. Just updating the mask is all that is
required as the following statement is a return.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>