defxx: Clean up DEFEA resource management

Reserve DEFEA resources according to actual use.  There are three
regions, for the ESIC ASIC's CSRs, for the discrete Burst Holdoff
register, and for the PDQ ASIC's CSRs.  The latter is mapped in the
memory or port I/O address space depending on configuration.  The two
formers are hardwired and always mapped in the port I/O address space.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>