vgabios: Report mode not supported getting mode informations

If you try to get mode information for an unsupported mode
interrupt should return error but not that the function is not
supported.

Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Committed-by: Keir Fraser <keir@xen.org>

tools/firmware/vgabios/vbe.c

@@ -909,7 +909,8 @@ Bit16u *AX;Bit16u ES;Bit16u DI;
 void vbe_biosfn_return_mode_information(AX, CX, ES, DI)
 Bit16u *AX;Bit16u CX; Bit16u ES;Bit16u DI;
 {
-        Bit16u            result=0x0100;
+        // error by default is 0x014f which means supported but error
+        Bit16u                 result=0x014f;
         Bit16u            ss=get_SS();
         ModeInfoBlock     info;
         ModeInfoListItem  *cur_info;
@@ -953,7 +954,6 @@ Bit16u *AX;Bit16u CX; Bit16u ES;Bit16u DI;
 #ifdef DEBUG
                 printf("VBE *NOT* found mode %x\n",CX);
 #endif
-                result = 0x100;
         }
         
         if (result == 0x4f)