libxl: Use the SUSE ovmf firmware path for Xen

The libxl driver trivially supports firmware autoselection since as of
June 2021 ovmf only supports one firmware for Xen. This patch adjusts
the firmware path to match the one provided by the ovmf package.


Index: libvirt-7.7.0/src/libxl/libxl_conf.c
===================================================================
--- libvirt-7.7.0.orig/src/libxl/libxl_conf.c
+++ libvirt-7.7.0/src/libxl/libxl_conf.c
@@ -1797,7 +1797,7 @@ libxlDriverConfigNew(void)
     cfg->firmwares = g_new0(virFirmware *, 1);
     cfg->nfirmwares = 1;
     cfg->firmwares[0] = g_new0(virFirmware, 1);
-    cfg->firmwares[0]->name = g_strdup(LIBXL_FIRMWARE_DIR "/ovmf.bin");
+    cfg->firmwares[0]->name = g_strdup(DATADIR "/qemu/ovmf-x86_64-xen-4m.bin");
 #endif
 
     /* Always add hvmloader to firmwares */