net: cadnece_gem: Update irq_read_clear field of designcfg_debug1 reg

Advertise support of clear-on-read for ISR registers.

Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/cadence_gem.c

@@ -1371,7 +1371,7 @@ static void gem_reset(DeviceState *d)
     s->regs[GEM_TXPARTIALSF] = 0x000003ff;
     s->regs[GEM_RXPARTIALSF] = 0x000003ff;
     s->regs[GEM_MODID] = s->revision;
-    s->regs[GEM_DESCONF] = 0x02500111;
+    s->regs[GEM_DESCONF] = 0x02D00111;
     s->regs[GEM_DESCONF2] = 0x2ab10000 | s->jumbo_max_len;
     s->regs[GEM_DESCONF5] = 0x002f2045;
     s->regs[GEM_DESCONF6] = GEM_DESCONF6_64B_MASK;