Description of problem:
If creating VM with "GiB", then setting "Current allocation" memory for a running VM will not take effect.

Version-Release number of selected components (if applicable):
cockpit-297-1.el8.ppc64le
cockpit-machines-297-1.el8.noarch
libvirt-dbus-1.3.0-2.module+el8.9.0+18724+20190c23.ppc64le

How reproducible:
100%

Steps to Reproduce:
1 Create a running VM with 2 GiB and Fedora 38, then enter the VM detail page
2 Click "edit" of "Memory", then change the "Current allocation" to 2038 MiB, then click "Save" on the dialog
3 Re-click "edit" to check the "Current allocation"
4 Check in the backend by "virsh dumpxml ${vm}"

Actual results:
1 After step 3, the "Current allocation" is still 2048
2 After step 4, the "memory" in the VM XML is also 2097152

Expected results:
1 After step 3, the "Current allocation" should be 2038
2 After step 4, the "memory" in the VM XML should be 2086912

Additional info: