net: add MMIO Register MDIO MUX driver

Add support for MMIO register MDIO muxes based on the Linux mdio-mux-mmioreg driver.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index a19511a..511c87c 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -43,6 +43,7 @@
 obj-$(CONFIG_MCFFEC) += mcffec.o mcfmii.o
 obj-$(CONFIG_MDIO_IPQ4019) += mdio-ipq4019.o
 obj-$(CONFIG_MDIO_MUX_I2CREG) += mdio_mux_i2creg.o
+obj-$(CONFIG_MDIO_MUX_MMIOREG) += mdio_mux_mmioreg.o
 obj-$(CONFIG_MDIO_MUX_SANDBOX) += mdio_mux_sandbox.o
 obj-$(CONFIG_MPC8XX_FEC) += mpc8xx_fec.o
 obj-$(CONFIG_MT7620_ETH) += mt7620-eth.o