Support ethernet and mbed client

Author: cyliangtw

hal/targets.json

@@ -1960,6 +1960,7 @@
         "supported_toolchains": ["ARM", "uARM", "GCC_ARM", "IAR"],
         "inherits": ["Target"],
         "progen": {"target": "numaker-pfm-nuc472"},
-        "device_has": ["ANALOGIN", "I2C", "I2CSLAVE", "I2C_ASYNCH", "INTERRUPTIN", "LOWPOWERTIMER", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SERIAL_FC", "SLEEP", "SPI", "SPISLAVE", "SPI_ASYNCH"]
+        "device_has": ["ANALOGIN", "I2C", "I2CSLAVE", "I2C_ASYNCH", "INTERRUPTIN", "LOWPOWERTIMER", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SERIAL_FC", "SLEEP", "SPI", "SPISLAVE", "SPI_ASYNCH"],
+        "features": ["IPV4"]
     }
 }

hal/targets/cmsis/TARGET_NUVOTON/TARGET_NUC472/TARGET_NUMAKER_PFM_NUC472/TOOLCHAIN_ARM_STD/NUC472.sct

@@ -22,7 +22,7 @@ LR_IROM1 0x00000000 {
 
   ; Too large to place into internal SRAM. So place into external SRAM instead.
   ER_XRAM1 0x60000000 {
-    *sal-stack-lwip* (+ZI)
+    *lwip_* (+ZI)
   }
 
   ; Extern SRAM for HEAP

hal/targets/cmsis/TARGET_NUVOTON/TARGET_NUC472/TARGET_NUMAKER_PFM_NUC472/TOOLCHAIN_GCC_ARM/NUC472.ld

@@ -235,7 +235,8 @@ SECTIONS
          * Place large .bss* sections into external SRAM if internal SRAM is insufficient.
          * Such memory arrangement requires initializing .bss.extern section to zero in startup file. Check startup fiile in cmsis-core-* for support or not.
          */
-        /* E.g.: ym/sal-stack-lwip/source/sal-stack-lwip.a(.bss*) */
+        *lwip_*.o(.bss*)
+        *lwip_*.o(COMMON)
         __bss_extern_end__ = .;
     } > RAM_EXTERN