btrfs: don't skip accounting in early ENOTTY return in btrfs_uring_encoded_read()

btrfs_uring_encoded_read() returns early with -ENOTTY if the uring_cmd
is issued with IO_URING_F_COMPAT but the kernel doesn't support compat
syscalls. However, this early return bypasses the syscall accounting.
Go to out_acct instead to ensure the syscall is counted.

Fixes: 34310c44 ("btrfs: add io_uring command for encoded reads (ENCODED_READ ioctl)")
CC: stable@vger.kernel.org # 6.15+
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>