ata: libata: Introduce ata_port_eh_scheduled()

ata: libata: Introduce ata_port_eh_scheduled()

Introduce the inline helper function ata_port_eh_scheduled() to test if
EH is pending (ATA_PFLAG_EH_PENDING port flag is set) or running
(ATA_PFLAG_EH_IN_PROGRESS port flag is set) for a port. Use this helper
in ata_port_wait_eh() and __ata_scsi_queuecmd() to replace the hardcoded
port flag tests.

No functional changes.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Link: https://lore.kernel.org/r/20250704104601.310643-1-dlemoal@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>