arm64: defconfig: enable taskstats configuration

Enable CONFIG_TASKSTATS which is required for CONFIG_TASK_XACCT (and
subsequently CONFIG_TASK_IO_ACCOUNTING). Previously, taskstats got
pulled in by KVM but that got changed in commit 63b3f96e
("kvm: Select SCHED_INFO instead of TASK_DELAY_ACCT").
Signed-off-by: NMarcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: NKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm64/configs/defconfig

@@ -7,6 +7,7 @@ CONFIG_PREEMPT=y
 CONFIG_IRQ_TIME_ACCOUNTING=y
 CONFIG_BSD_PROCESS_ACCT=y
 CONFIG_BSD_PROCESS_ACCT_V3=y
+CONFIG_TASKSTATS=y
 CONFIG_TASK_XACCT=y
 CONFIG_TASK_IO_ACCOUNTING=y
 CONFIG_IKCONFIG=y