sata_sx4: pdc20621_{ata|host}_sg() do not need 'tf' parameter

... because those functions don't use this parameter.

While at it, correctly align 'total_len' parameter.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>