brcm63xx: provide a default sane MAC address for Cable Modem devices

Cable modem devices currently poke at some random location in RAM and
may end up having an invalid MAC address which is not suitable. Provide
a default one which is sane.

Signed-off-by: Florian Fainelli <florian@openwrt.org>

SVN-Revision: 36957

target/linux/brcm63xx/patches-3.9/426-hcs_mac_addr_pool.patch

+--- a/arch/mips/bcm63xx/nvram.c
++++ b/arch/mips/bcm63xx/nvram.c
+@@ -52,6 +52,7 @@ void __init bcm63xx_nvram_init(void *add
+ {
+ 	unsigned int check_len;
+ 	u32 crc, expected_crc;
++	u8 hcs_mac_addr[ETH_ALEN] = { 0x00, 0x10, 0x18, 0xff, 0xff, 0xff };
+ 
+ 	/* extract nvram data */
+ 	memcpy(&nvram, addr, sizeof(nvram));
+@@ -73,6 +74,15 @@ void __init bcm63xx_nvram_init(void *add
+ 	if (crc != expected_crc)
+ 		pr_warn("nvram checksum failed, contents may be invalid (expected %08x, got %08x)\n",
+ 			expected_crc, crc);
++
++	/* Cable modems have a different NVRAM which is embedded in the eCos
++	 * firmware and not easily extractible, give at least a MAC address
++	 * pool.
++	 */
++	if (BCMCPU_IS_3368()) {
++		memcpy(nvram.mac_addr_base, hcs_mac_addr, ETH_ALEN);
++		nvram.mac_addr_count = 2;
++	}
+ }
+ 
+ u8 *bcm63xx_nvram_get_name(void)