[Nuvoton] Remove SD component from targets.json
[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

andcor02/mbed-os,andcor02/mbed-os,andcor02/mbed-os,kjbracey-arm/mbed,andcor02/mbed-os,andcor02/mbed-os,kjbracey-arm/mbed,kjbracey-arm/mbed,mbedmicro/mbed,mbedmicro/mbed,kjbracey-arm/mbed,andcor02/mbed-os,mbedmicro/mbed,mbedmicro/mbed,mbedmicro/mbed