ar71xx/mikrotik: disable unused ethernet switch and phy drivers

Disable the drivers for the following ethernet switches:
  Realtek RTL8306
  Realtek RTL8366/8367
  Marvell 88E6060 (DSA)
  Marvell 88E6063 (DSA)

Also disable the phy driver for Marvell PHYs.

None of the supported RouterBOARDs are using any device
which needs these drivers.

Disable the DSA framework too, because it is not required
by the remaining switch drivers.

This reduces the compressed kernel size by ~20KB.

Signed-off-by: Gabor Juhos <juhosg@freemail.hu>

target/linux/ar71xx/mikrotik/config-default

@@ -220,6 +220,7 @@ CONFIG_GPIO_LATCH=y
 # CONFIG_INTEL_XWAY_PHY is not set
 CONFIG_LEDS_RB750=y
 CONFIG_LZO_DECOMPRESS=y
+# CONFIG_MARVELL_PHY is not set
 # CONFIG_MTD_CFI is not set
 CONFIG_MTD_CFI_I2=y
 # CONFIG_MTD_CYBERTAN_PARTS is not set
@@ -243,7 +244,10 @@ CONFIG_MTD_UBI_BLOCK=y
 # CONFIG_MTD_UBI_FASTMAP is not set
 # CONFIG_MTD_UBI_GLUEBI is not set
 CONFIG_MTD_UBI_WL_THRESHOLD=4096
+# CONFIG_NET_DSA is not set
 CONFIG_RLE_DECOMPRESS=y
+# CONFIG_RTL8306_PHY is not set
+# CONFIG_RTL8366_SMI is not set
 # CONFIG_SOC_AR913X is not set
 # CONFIG_SOC_AR933X is not set
 # CONFIG_SOC_QCA956X is not set