drivers/net: delete old DEC depca ISA drivers support.

These are old ISA 10Mbit cards from the 1st 1/2 of the 1990s and
required manual jumper settings in order to configure them.  Here
we remove them on the premise that they are no longer used in any
modern 3.9+ kernels.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>