ATA DMA support

[michalusio]

Currently the ATA basic driver uses ATA-PIO mode, which needs the CPU to move each word from IO to RAM. We can make this a lot faster by implementing DMA support. That would require:

1. Implementing DMA calls for the ATA driver (or making a new driver)
2. Extending the ATA interrupt so it responds to the data request
3. Probably implement some kind of IO queue of commands to performs (maybe using kernel threads?)