ARM: l2c: use L2C-210 handlers for L2C-310 errata-less implementations

Where no errata affect the L2C-310 handlers, they are functionally
equivalent to L2C-210.  Re-use the L2C-210 handlers for the L2C-310
part.

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