powerpc: mpc8xx: remove hermes board support

This board sprinkles #ifdef(CONFIG_HERMES) over various global files
such as include/common.h, common/board_r.c, common/cmd_bdinfo.c.
Let's zap such an ill-behaved board.

It has not been converted to generic board yet and mpc8xx is old
enough.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Wolfgang Denk <wd@denx.de>
Acked-by: Wolfgang Denk <wd@denx.de>