common/board_f: enable setup_board_part1() for MIPS

The variables bd_t:bi_memstart and bd_t:bi_memsize have to be
initialized also on MIPS. Otherwise LMB and cmd_bdinfo do not
correctly work. This currently breaks the booting of FIT images
on MIPS. Enable the board_init_f hook setup_board_part1()
for MIPS to fix this.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>