pata_ipx4xx_cf: Fix unsigned comparison with less than zero

pata_ipx4xx_cf: Fix unsigned comparison with less than zero

The return from the call to platform_get_irq() is int, it can be
a negative error code, however this is being assigned to an unsigned
int variable 'irq', so making 'irq' an int, and change the position to
keep the code format.

./drivers/ata/pata_ixp4xx_cf.c:168:5-8:
WARNING: Unsigned expression compared with zero: irq > 0

Signed-off-by: Junlin Yang <yangjunlin@yulong.com>
Link: https://lore.kernel.org/r/20210409135426.1773-1-angkery@163.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>