[coverity] Remove no effect code

This PR fixes the Coverity issue, indicating no effect code

**Changes proposed in this PR:**
- Remove negative check (unsigned int is always non-negative).

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

Signed-off-by: Donghyeon Jeong <[email protected]>

nntrainer/tensor/tensor_v2.cpp

@@ -263,7 +263,7 @@ const std::array<size_t, TensorDim::MAXDIM> TensorV2::getStrides() const
 }
 
 bool TensorV2::checkContinuous(unsigned int np1, unsigned int np2) const {
-  if (np1 < 0 || np1 > 3 || np2 < 0 || np2 > 3) {
+  if (np1 > 3 || np2 > 3) {
     throw std::invalid_argument(
       "Error: Input value must be within the range of 0 to 3.");
   }