arm: rmobile: lager: Remove NOR-Flash support from boards.cfg

Lager board has NOR-Flash function. But this is not used basically.
SPI-ROM is used instead. NOR-Flash support code has been removed, but
this remains in the boards.cfg.
This commit removes config of NOR-Flash from boards.cfg.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>