broadcom: Add BCM63146 chip support
As a side effect of a try of CONFIG_BCM_CHIP_ID removal I've added BCM63146 chip support.
It looks like with this addition commit 69f40124 may be reverted.
After getting rid of CONFIG_BCM_CHIP_ID feeds Makefile passes -DCONFIG_BCM<CHIP_ID>.
We can remove unused CHIP_xxxx then.
Same time we can fix workaround: 69f40124. ("libdsl: define CONFIG_VDSL_SUPPORTED explicitly")
Edited by Piotr Kubik