net: stmmac: dwmac4/5: Do not disable whole RX in dma_stop_rx()

We don't need to disable the whole RX when dma_stop_rx() is called
because there may be the need of just disabling 1 DMA channel.

This is also needed for stmmac Flow Control selftest.
Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Cc: Joao Pinto <jpinto@synopsys.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c

@@ -88,10 +88,6 @@ void dwmac4_dma_stop_rx(void __iomem *ioaddr, u32 chan)
 
 	value &= ~DMA_CONTROL_SR;
 	writel(value, ioaddr + DMA_CHAN_RX_CONTROL(chan));
-
-	value = readl(ioaddr + GMAC_CONFIG);
-	value &= ~GMAC_CONFIG_RE;
-	writel(value, ioaddr + GMAC_CONFIG);
 }
 
 void dwmac4_set_tx_ring_len(void __iomem *ioaddr, u32 len, u32 chan)