[dataset] Clean up dataset enums

[dataset] Clean up dataset enums

`nntrainer::DataType` and `nntrainer::BufferType` is duplicated from
ccapi which was adding complication. This patch simply alternate those
types ccapi `DatasetType` / `DatasetDataUsageType`

**Self evaluation:**
1. Build test: [X]Passed [ ]Failed [ ]Skipped
2. Run test: [X]Passed [ ]Failed [ ]Skipped

Signed-off-by: Jihoon Lee <jhoon.it.lee@samsung.com>