Add PPC2_FEATURE2_ARCH_3_10 to the PowerPC AT_HWCAP2 definitions.

Signed-off-by: Lijun Pan <ljp@linux.ibm.com>
Message-Id: <20200724045845.89976-2-ljp@linux.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>