BACKPORT: FROMLIST: block/bfq: Enable I/O statistics

BFQ uses io_start_time_ns. That member variable is only set if I/O
statistics are enabled. Hence this patch that enables I/O statistics
at the time BFQ is associated with a request queue.

Compile-tested only.

Reported-by: Cixi Geng <cixi.geng1@unisoc.com>
Cc: Cixi Geng <cixi.geng1@unisoc.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Yu Kuai <yukuai3@huawei.com>
Cc: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[ bvanassche: Left out the blk_stat_disable_accounting() call since ]
[ commit 68497092 ("block: make queue stat accounting a         ]
[ reference") from kernel v5.17 has not been backported to the      ]
[ android13-5.15 branch.                                            ]
Bug: 235453574
Link: https://lore.kernel.org/linux-block/20220613163234.3593026-1-bvanassche@acm.org/T/#u


Change-Id: I5fad0fb3c7e9c6007aadd94ebb73d91c41143549
Signed-off-by: Bart Van Assche <bvanassche@google.com>