eth-raw-os.c: Add cast to bind(2) call

eth-raw-os.c: Add cast to bind(2) call

With more recent gcc versions we otherwise get an error like:
note: expected 'const struct sockaddr *' but argument is of type
'struct sockaddr_in *'

and the common solution here is to cast, rather than re-work the code.

Cc: Joe Hershberger <joe.hershberger@ni.com>
Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>