When erase/trim/discard completion was converted to mmc_poll_for_busy(),
optional support to poll with the host_ops->card_busy() callback was also
added.

The common sdhci's ->card_busy() turns out not to be working as expected
for the sdhci-brcmstb variant, as it keeps returning busy beyond the card's
busy period. In particular, this leads to the below splat for
mmc_do_erase() when running a discard (BLKSECDISCARD) operation during
mkfs.f2fs:

    Info: [/dev/mmcblk1p9] Discarding device
    [   39.597258] sysrq: Show Blocked State
    [   39.601183] task:mkfs.f2fs       state:D stack:0     pid:1561  tgid:1561  ppid:1542   flags:0x0000000d
    [   39.610609] Call trace:
    [   39.613098]  __switch_to+0xd8/0xf4
    [   39.616582]  __schedule+0x440/0x4f4
    [   39.620137]  schedule+0x2c/0x48
    [   39.623341]  schedule_hrtimeout_range_clock+0xe0/0x114
    [   39.628562]  schedule_hrtimeout_range+0x10/0x18
    [   39.633169]  usleep_range_state+0x5c/0x90
    [   39.637253]  __mmc_poll_for_busy+0xec/0x128
    [   39.641514]  mmc_poll_for_busy+0x48/0x70
    [   39.645511]  mmc_do_erase+0x1ec/0x210
    [   39.649237]  mmc_erase+0x1b4/0x1d4
    [   39.652701]  mmc_blk_mq_issue_rq+0x35c/0x6ac
    [   39.657037]  mmc_mq_queue_rq+0x18c/0x214
    [   39.661022]  blk_mq_dispatch_rq_list+0x3a8/0x528
    [   39.665722]  __blk_mq_sched_dispatch_requests+0x3a0/0x4ac
    [   39.671198]  blk_mq_sched_dispatch_requests+0x28/0x5c
    [   39.676322]  blk_mq_run_hw_queue+0x11c/0x12c
    [   39.680668]  blk_mq_flush_plug_list+0x200/0x33c
    [   39.685278]  blk_add_rq_to_plug+0x68/0xd8
    [   39.689365]  blk_mq_submit_bio+0x3a4/0x458
    [   39.693539]  __submit_bio+0x1c/0x80
    [   39.697096]  submit_bio_noacct_nocheck+0x94/0x174
    [   39.701875]  submit_bio_noacct+0x1b0/0x22c
    [   39.706042]  submit_bio+0xac/0xe8
    [   39.709424]  blk_next_bio+0x4c/0x5c
    [   39.712973]  blkdev_issue_secure_erase+0x118/0x170
    [   39.717835]  blkdev_common_ioctl+0x374/0x728
    [   39.722175]  blkdev_ioctl+0x8c/0x2b0
    [   39.725816]  vfs_ioctl+0x24/0x40
    [   39.729117]  __arm64_sys_ioctl+0x5c/0x8c
    [   39.733114]  invoke_syscall+0x68/0xec
    [   39.736839]  el0_svc_common.constprop.0+0x70/0xd8
    [   39.741609]  do_el0_svc+0x18/0x20
    [   39.744981]  el0_svc+0x68/0x94
    [   39.748107]  el0t_64_sync_handler+0x88/0x124
    [   39.752455]  el0t_64_sync+0x168/0x16c

To fix the problem let's override the host_ops->card_busy() callback by
setting it to NULL, which forces the mmc core to poll with a CMD13 and
checking the R1_STATUS in the mmc_busy_cb() function.
Signed-off-by: Kamal Dasu <kamal.dasu@broadcom.com>
Fixes: 0d84c3e6 ("mmc: core: Convert to mmc_poll_for_busy() for erase/trim/discard")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240603220834.21989-2-kamal.dasu@broadcom.com
[Ulf: Clarified the commit message]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>