division by zero in ide
Description of problem:
The following log reveals it:

```
../hw/ide/core.c:659:26: runtime error: division by zero
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ../hw/ide/core.c:659:26 in AddressSanitizer:DEADLYSIGNAL ================================================================= 
==4104568==ERROR：AddressSanitizer：FPE on unknown address 0x559d996a7ec3 (pc 0x559d996a7ec3 bp 0x7ffdcf109da0 sp 0x7ffdcf109a40 T0) 
#0 0x559d996a7ec3 in ide_set_sector qemu/hw/ide/core.c:659:26 
#1 0x559d996c8dee in ide_sector_read_cb qemu/hw/ide/core.c:786:5 
#2 0x559d996aa50a in ide_buffered_readv_cb qemu/hw/ide/core.c:684:9 
#3 0x559d9b499289 in blk_aio_complete qemu/block/block-backend.c:1555:9 
#4 0x559d9b4891af in blk_aio_complete_bh qemu/block/block-backend.c:1565:5 
#5 0x559d9bbef6b1 in aio_bh_call qemu/util/async.c:171:5 
#6 0x559d9bbf058c in aio_bh_poll qemu/util/async.c:218:13 
#7 0x559d9bb58a28 in aio_dispatch qemu/util/aio-posix.c:423:5 
#8 0x559d9bbf69ce in aio_ctx_dispatch qemu/util/async.c:360:5 
#9 0x7f51fbc77d3a in g_main_context_dispatch (/lib/x86_64-linux-gnu/libglib-2.0.so.0) +0x55d3a.+0x55d3a) 
#10 0x559d9bbfa229 in glib_pollfds_poll qemu/util/main-loop.c:287:9 
#11 0x559d9bbf8b63 in os_host_main_loop_wait qemu/util/main-loop.c:310:5 
#12 0x559d9bbf872c in main_loop_wait qemu/util/main-loop.c:589:11 
#13 0x559d9a2640e7 in qemu_main_loop qemu/system/runstate.c:796:9 
#14 0x559d9b1dcaec in qemu_default_main qemu/system/main.c:37:14 
#15 0x559d9b1dcb37 in main qemu/system/main.c:48:12 
#16 0x7f51fb229d8f in __libc_start_call_main csu/.../sysdeps/nptl/libc_start_call_main.h:58:16 
#17 0x7f51fb229e3f in __libc_start_main csu/../csu/libc-start.c:392:3 #18 0x559d98f20ed4 in _start (/home/joey/repo/qemu/build/qemu-system-x86_64+0x1f93ed4)
```