net: stmmac: Re-word Kconfig entry

We support many speeds and it doesn't make much sense to list them all
in the Kconfig. Let's just call it Multi-Gigabit.
Suggested-by: David S. Miller <davem@davemloft.net>
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/Kconfig

 # SPDX-License-Identifier: GPL-2.0-only
 config STMMAC_ETH
-	tristate "STMicroelectronics 10/100/1000/EQOS/2500/5000/10000 Ethernet driver"
+	tristate "STMicroelectronics Multi-Gigabit Ethernet driver"
 	depends on HAS_IOMEM && HAS_DMA
 	select MII
 	select PHYLINK