ARM: 7162/1: errata: tidy up Kconfig options for PL310 errata workarounds

The Kconfig options for the PL310 errata workarounds do not use a
consistent naming scheme for either the config option or the bool
description.

This patch tidies up the options by ensuring that the bool descriptions
are prefixed with "PL310 errata:" and the config options are prefixed
with PL310_ERRATA_, making it much clearer in menuconfig as to what the
workarounds are for.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>