NetStar: eeprom - undefined reference to `memset'

Defining partially initialized struct eth_device on stack means
gcc has to zero out it, and some gcc versions optimize this with
an implicit call to memset. Move definition to data section
to avoid that (it has also nice side effect that we need not
to pass it to helper functions anymore)

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>