Initialize pci_dev

Else it is read before initialization if XSERVER_LIBPCIACCESS is not
defined or location.type is not BUS_PCI.

Noticed when I got a segfault where it was 0x1 while doing some tests on
arm.
Signed-off-by: Pascal Terjan <pterjan@google.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>

src/fbdev.c

@@ -427,7 +427,7 @@ FBDevPreInit(ScrnInfoPtr pScrn, int flags)
 	int default_depth, fbbpp;
 	const char *s;
 	int type;
-	void *pci_dev;
+	void *pci_dev = NULL;
 
 	if (flags & PROBE_DETECT) return FALSE;