node_device_conf: Don't prealloc @vfs in virNodeDeviceGetPCISRIOVCaps()

node_device_conf: Don't prealloc @vfs in virNodeDeviceGetPCISRIOVCaps()

The array of virtual functions @vfs in
virNodeDeviceGetPCISRIOVCaps() is allocated twice: the first time
during its declaration and the second time inside
virPCIGetVirtualFunctions() which leads to a memleak:

==16691== 1,128 bytes in 47 blocks are definitely lost in loss record 1,771 of 1,803
==16691==    at 0x4844CC1: calloc (vg_replace_malloc.c:1117)
==16691==    by 0x4E50070: g_malloc0 (in /usr/lib64/libglib-2.0.so.0.6800.3)
==16691==    by 0x4A7B034: virNodeDeviceGetPCISRIOVCaps (node_device_conf.c:2649)
==16691==    by 0x4A7B5E2: virNodeDeviceGetPCIDynamicCaps (node_device_conf.c:2762)
==16691==    by 0xA7F6E18: udevProcessPCI (node_device_udev.c:418)

Fixes: c97518d9b833a607f29b9bb02e3fbe74c011c088
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>