bsp: k230: fix kconfig warnings
scons --menuconfig will report:
```
warning: the choice symbol PKG_USING_ZLIB_LATEST_VERSION
(defined at /home/u/.env/packages/packages/misc/zlib/Kconfig:31)
is selected by the following symbols, but select/imply has no
effect on choice symbols
- BSP_ROOTFS_TYPE_CROMFS (defined at Kconfig:36)
warning: default on the choice symbol BSP_USING_SDIO0
(defined at board/Kconfig:20) will have no effect, as defaults
do not affect choice symbols
warning: default on the choice symbol BSP_USING_SDIO1
(defined at board/Kconfig:34) will have no effect, as defaults
do not affect choice symbols
```
Fix and remove these warnings.
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
Chen Wang