vm-util: fix vmm module detection

[Wrench56]

Fixes a long-standing bug.

As seen below, the method to use kdlstat -qm vmm does not actually catch the loaded vmm.ko module. For some reason, kldstat -qn vmm or the more verbose kldstat -qn vmm.ko does. Without much change, I added a way to use the -qn flag for vmm specifically, but not for other modules that would break using the -qn flag (nmdm, if_bridge, if_tuntap, if_tap).

$ kldstat
Id Refs Address                Size Name
 1   54 0xffffffff80200000  1f4daa0 kernel
 2    1 0xffffffff8214e000    1c708 geom_eli.ko
 3    1 0xffffffff8216b000   620c10 zfs.ko
 4    1 0xffffffff83310000     3390 acpi_wmi.ko
 5    1 0xffffffff83314000     21e8 hcons.ko
 6    2 0xffffffff83317000     30a8 hidmap.ko
 7    1 0xffffffff8331b000     21e8 hsctrl.ko
 8    1 0xffffffff8331e000     4250 ichsmb.ko
 9    1 0xffffffff83323000     2178 smbus.ko
10    1 0xffffffff83326000     2110 pchtherm.ko
11    1 0xffffffff83329000     2a80 mac_ntpd.ko
12    2 0xffffffff8332c000    64bc8 pf.ko
13    1 0xffffffff83391000     21e8 pflog.ko
14    1 0xffffffff83400000   340438 vmm.ko
$ kldstat -qm vmm
$ echo "$?"
1
$ kldstat -qn vmm
$ echo "$?"
0

Although the issue I linked talks about FreeBSD version 12.0, it very much still persists on newer versions:

FreeBSD ******** 15.0-RELEASE FreeBSD 15.0-RELEASE releng/15.0-n280995-7aedc8de6446 GENERIC amd64