brcm63xx: Add Huawei HG655b support

This patch adds support for the Huawei HG655b.

Nothing much special in this router, it's just another BCM6368 with
a Ralink RT3062 wifi chip and the calibration data embedded in the
main flash chip at offset 0x7c0000. There is also configuration data
used by the OEM firmware before the cal_data partition, this area is
protected by the board_data partition in this patch.

Signed-off-by: Daniel Gonzalez <dgcbueu@gmail.com>
Signed-off-by: Jonas Gorski <jogo@openwrt.org>

SVN-Revision: 45708