quota: Fix rcu annotations of inode dquot pointers

Dquot pointers in i_dquot array in the inode are protected by
dquot_srcu. Annotate the array pointers with __rcu, perform the locked
dereferences with srcu_dereference_check() instead of plain reads, and
set the array elements with rcu_assign_pointer().

Fixes: b9ba6f94 ("quota: remove dqptr_sem")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202402061900.rTuYDlo6-lkp@intel.com/


Signed-off-by: Jan Kara <jack@suse.cz>