This resolves the build error
```
arm-none-eabi-ld: build-spresense/libmpy.a(Camera.o):(.rodata.camera_imageformat_type+0x0): multiple definition of `camera_imageformat_type'; build-spresense/libmpy.a(__init__.o):(.rodata.camera_imageformat_type+0x0): first defined here
arm-none-eabi-ld: build-spresense/libmpy.a(ImageFormat.o):(.rodata.camera_imageformat_type+0x0): multiple definition of `camera_imageformat_type'; build-spresense/libmpy.a(__init__.o):(.rodata.camera_imageformat_type+0x0): first defined here
arm-none-eabi-ld: build-spresense/libmpy.a(Camera.o):(.rodata.camera_imageformat_type+0x0): multiple definition of `camera_imageformat_type'; build-spresense/libmpy.a(__init__.o):(.rodata.camera_imageformat_type+0x0): first defined here
```
