ARM: l2c: remove platforms/SoCs setting early BRESP

Since we now automatically enable early BRESP in core L2C-310 code when
we detect a Cortex-A9, we don't need platforms/SoCs to set this bit
explicitly.  Instead, they should seek to preserve the value of bit 30
in the auxiliary control register.

Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>