Add mbed_lib.json config to avoid emac drivers source includes by default

Author: rajkan01

connectivity/drivers/emac/TARGET_ARM_FM/COMPONENT_LAN91C111/mbed_lib.json

@@ -0,0 +1,3 @@
+{
+    "name": "lan91c111-emac"
+}

connectivity/drivers/emac/TARGET_Cypress/mbed_lib.json

@@ -0,0 +1,3 @@
+{
+    "name": "cypress-emac"
+}

connectivity/drivers/emac/TARGET_GD_EMAC/mbed_lib.json

@@ -0,0 +1,3 @@
+{
+    "name": "gd-emac"
+}

connectivity/drivers/emac/TARGET_NUVOTON_EMAC/mbed_lib.json

@@ -0,0 +1,3 @@
+{
+    "name": "nuvoton-emac"
+}

connectivity/drivers/emac/TARGET_NXP_EMAC/TARGET_LPCTarget/mbed_lib.json

@@ -0,0 +1,3 @@
+{
+    "name": "lpc17-emac"
+}

connectivity/drivers/emac/TARGET_NXP_EMAC/TARGET_MCU_LPC546XX/mbed_lib.json

@@ -0,0 +1,3 @@
+{
+    "name": "lpc546xx-emac"
+}

connectivity/drivers/emac/TARGET_RDA_EMAC/mbed_lib.json

@@ -0,0 +1,3 @@
+{
+    "name": "rda5981x-emac"
+}

connectivity/drivers/emac/TARGET_RZ_A1_EMAC/mbed_lib.json

@@ -0,0 +1,3 @@
+{
+    "name": "rza1-emac"
+}