h8300: normalize global variables exported by vmlinux.lds

Generate mandatory global variables __bss_start/__bss_stop in
file vmlinux.lds.

Also remove one unused declaration of _text.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>