ARM: l2c: convert Broadcom L2C-310 to new code

The Broadcom L2C-310 devices use ARMs L2C-310 R2P3 or later.  These
require no errata workarounds, and so we can directly call the l2c210
functions from their methods.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>