fpga: altera: Add some more device sizes

There seems to be only one place, where this is checked against:
`altera_validate()`. It should be non zero. Otherwise it is only used to
display it, so it probably does not really matter at the moment. But we
had the datasheet open anyway …

Sizes in datasheet are bit counts, display here is in bytes.

Signed-off-by: Alexander Dahl <ada@thorsis.com>