tune-cortexa57-cortexa53.inc: add CRC and set march

tune-cortexa57-cortexa53.inc: add CRC and set march

Add CRC to the default tuning of big.LITTLE Cortex-A57-A53.  This puts
it inline with all other ARMv8a tunings.  Also, reference
PACKAGE_EXTRA_ARCHS_tune-armv8a-crc instead of
PACKAGE_EXTRA_ARCHS_tune-aarch64, which sets the -march to armv8 and
enables the CRC.

Signed-off-by: Jon Mason <jon.mason@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>