hw/nvme: fix memory leak in nvme_dsm

hw/nvme: fix memory leak in nvme_dsm

The allocated memory to hold LBA ranges leaks in the nvme_dsm function. This
happens because the allocated memory for iocb->range is not freed in all
error handling paths.

Fix this by adding a free to ensure that the allocated memory is properly freed.

ASAN log:
==3075137==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 480 byte(s) in 6 object(s) allocated from:
    #0 0x55f1f8a0eddd in malloc llvm/compiler-rt/lib/asan/asan_malloc_linux.cpp:129:3
    #1 0x7f531e0f6738 in g_malloc (/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x5e738)
    #2 0x55f1faf1f091 in blk_aio_get block/block-backend.c:2583:12
    #3 0x55f1f945c74b in nvme_dsm hw/nvme/ctrl.c:2609:30
    #4 0x55f1f945831b in nvme_io_cmd hw/nvme/ctrl.c:4470:16
    #5 0x55f1f94561b7 in nvme_process_sq hw/nvme/ctrl.c:7039:29

Cc: qemu-stable@nongnu.org
Fixes: d7d1474fd85d ("hw/nvme: reimplement dsm to allow cancellation")
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
(cherry picked from commit c510fe78f1b7c966524489d6ba752107423b20c8)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>