ARM: BCM5301X: activate some additional options in pl310 cache controller

In the default Broadcom SDK the shared override is activated for this
cache controller, do the same in the upstream code. Data and
instruction prefetching is not activated by default for this cache
controller on the bcm53xx SoC, do it manually like it is done in the
vendor SDK.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>