CVE-2024-39476 md/raid5: fix deadlock that raid5d() wait for itself to clear MD_SB_CHANGE_PENDING

In the Linux kernel, the following vulnerability has been resolved: md/raid5: fix deadlock that raid5d wait for itself to clear MDSBCHANGEPENDING Xiao reported that lvm2 test lvconvert-raid-takeover.sh can hang with small possibility, the root cause is exactly the same as commit bed9e27baf52...