ata: pata_platform: Make use of platform_get_mem_or_io()

Make use of platform_get_mem_or_io() to simplify the code.

While at it, drop use of unlikely() from pata_platform_probe()
as it isn't a hotpath.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>