[Nuvoton] Remove SD component from targets.json

Nuvoton targets below don't provide SPI-bus SD on-board, identified by 'SD' in
target component list. Instead, these targets provide SD-bus SD on-board, identified
by unofficial 'NUSD', driver of which is provided outside mbed-os tree. So 'SD' must
be removed to reflect the truth.

- NUMAKER_PFM_NUC472
- NUMAKER_PFM_M487
- NUMAKER_IOT_M487
- NUMAKER_PFM_M2351

targets/targets.json

@@ -7121,7 +7121,7 @@
     },
     "NUMAKER_PFM_NUC472": {
         "core": "Cortex-M4F",
-        "components_add": ["SD", "FLASHIAP"],
+        "components_add": ["FLASHIAP"],
         "default_toolchain": "ARM",
         "extra_labels": [
             "NUVOTON",
@@ -7705,7 +7705,7 @@
     },
     "NUMAKER_PFM_M487": {
         "inherits": ["MCU_M480"],
-        "components_add": ["SD", "FLASHIAP"],
+        "components_add": ["FLASHIAP"],
         "device_name": "M487JIDAE"
     },
     "NUMAKER_IOT_M487": {