xfree86: vgaarb: Initialize local variable rsrc_decodes

In function xf86VGAarbiterScrnInit when the "pEnt->bus.type" is
BUS_PLATFORM, the "pScrn->vgaDev" won't be set, so the "pScrn->vgaDev" is
equal to zero.

The variable "rsrc_decodes" in function "xf86VGAarbiterAllowDRI" is not
initialized. So it will occur error when "pScrn->vgaDev == 0", and
"vga_count > 1". For this case, as "pScrn->vgaDev == 0", the function
"pci_device_vgaarb_get_info" will only set the value of "vga_count",
but won't set the value of "rsrc_decodes", so it will has two different
return values for function "xf86VGAarbiterAllowDRI" in different
platforms. One platform will return TRUE, as the "rsrc_decodes" 's
default value is 0, but another platform will return FALSE, as the
"rsrc_decodes" 's default value is "32767", this will cause disable
direct rendering.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96937

Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>

hw/xfree86/common/xf86VGAarbiter.c

@@ -105,7 +105,7 @@ Bool
 xf86VGAarbiterAllowDRI(ScreenPtr pScreen)
 {
     int vga_count;
-    int rsrc_decodes;
+    int rsrc_decodes = 0;
     ScrnInfoPtr pScrn = xf86ScreenToScrn(pScreen);
 
     if (vga_no_arb)