bdinfo: x86: Use the generic bd command

bdinfo: x86: Use the generic bd command

This arch shows 'ethspeed' info but only the freescale drivers use it, so
it can be dropped.

It also calls print_bi_dram() which is safe to call from any arch since it
has an #ifdef inside it. Add this to the generic do_bdinfo() and move x86
over to use it. Put it first since pytests rely on seeing it before
memstart in find_ram_base().

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>