hw/i386/amd_iommu: Don't leak memory in amdvi_update_iotlb()

hw/i386/amd_iommu: Don't leak memory in amdvi_update_iotlb()

In amdvi_update_iotlb() we will only put a new entry in the hash
table if to_cache.perm is not IOMMU_NONE.  However we allocate the
memory for the new AMDVIIOTLBEntry and for the hash table key
regardless.  This means that in the IOMMU_NONE case we will leak the
memory we alloacted.

Move the allocations into the if() to the point where we know we're
going to add the item to the hash table.

Cc: qemu-stable@nongnu.org
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2452
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20240731170019.3590563-1-peter.maydell@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 9a45b0761628cc59267b3283a85d15294464ac31)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>