ARM: dts: BCM5301X: Linksys EA9500 add fixed partitions

This router has dual paritions to store trx firmware image and
dual partitions for nvram. The second one in each of these cases acts
as a backup store.

When tested with OpenWrt, the default partition parser causes two issues:

1. It labels both nvram partitions as nvram. In factory, second one is
labeled devinfo.
2. It parses second trx image and tries to create second 'linux' partition
and fails with - cannot create duplicate 'linux' partition

The following patch works around both of these issues.

Signed-off-by: Vivek Unune <npcomplete13@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>