cirrus_vga: do not reset videoram

There is no need to set the videoram to 0xff in cirrus_reset, because it
is the BIOS' job.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NAvi Kivity <avi@redhat.com>

hw/cirrus_vga.c

@@ -2767,10 +2767,6 @@ static void cirrus_reset(void *opaque)
     }
     s->vga.cr[0x27] = s->device_id;
 
-    /* Win2K seems to assume that the pattern buffer is at 0xff
-       initially ! */
-    memset(s->vga.vram_ptr, 0xff, s->real_vram_size);
-
     s->cirrus_hidden_dac_lockindex = 5;
     s->cirrus_hidden_dac_data = 0;
 }