ata: make transfer mode masks *unsigned int*

The packed transfer mode masks and also the {pio|mwdma|udma}_mask fields
of *struct*s ata_device and ata_port_info are declared as *unsigned long*
(which is a 64-bit type on 64-bit architectures) but actually the packed
masks occupy only 20 bits (7 PIO modes, 5 MWDMA modes, and 8 UDMA modes)
and the PIO/MWDMA/UDMA masks easily fit into just 8 bits each, so we can
safely use (always 32-bit) *unsigned int* variables instead.  This saves
745 bytes of object code in libata-core.o alone, not to mention LLDDs...

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>