HIP: remove the use of __HIP_PLATFORM_AMD__, explicitly support only AMD targets (#14945)

ggml/src/ggml-cuda/vendors/hip.h

@@ -5,10 +5,8 @@
 #include <hipblas/hipblas.h>
 #include <hip/hip_fp16.h>
 #include <hip/hip_bfloat16.h>
-#ifdef __HIP_PLATFORM_AMD__
 // for rocblas_initialize()
 #include "rocblas/rocblas.h"
-#endif // __HIP_PLATFORM_AMD__
 
 #define CUBLAS_GEMM_DEFAULT HIPBLAS_GEMM_DEFAULT
 #define CUBLAS_GEMM_DEFAULT_TENSOR_OP HIPBLAS_GEMM_DEFAULT
@@ -139,7 +137,7 @@
 #define CUBLAS_STATUS_INTERNAL_ERROR HIPBLAS_STATUS_INTERNAL_ERROR
 #define CUBLAS_STATUS_NOT_SUPPORTED HIPBLAS_STATUS_NOT_SUPPORTED
 
-#if defined(__HIP_PLATFORM_AMD__) && HIP_VERSION >= 70000000
+#if HIP_VERSION >= 70000000
 #define CUBLAS_COMPUTE_16F HIPBLAS_COMPUTE_16F
 #define CUBLAS_COMPUTE_32F HIPBLAS_COMPUTE_32F
 #define CUBLAS_COMPUTE_32F_FAST_16F HIPBLAS_COMPUTE_32F_FAST_16F
@@ -151,7 +149,11 @@
 #define CUBLAS_COMPUTE_32F_FAST_16F HIPBLAS_R_32F
 #define cublasComputeType_t hipblasDatatype_t
 #define cudaDataType_t hipblasDatatype_t
-#endif
+#endif // HIP_VERSION >= 7000000
+
+#if !defined(__HIP_PLATFORM_AMD__)
+#error "The HIP backend supports only AMD targets"
+#endif // !defined(__HIP_PLATFORM_AMD__)
 
 #define __CUDA_ARCH__ 1300
 
@@ -249,7 +251,7 @@ static __device__ __forceinline__ unsigned int __vcmpne4(unsigned int a, unsigne
     return c;
 }
 
-#if defined(__HIP_PLATFORM_AMD__) && HIP_VERSION < 50600000
+#if HIP_VERSION < 50600000
 // __shfl_xor() for half2 was added in ROCm 5.6
 static __device__ __forceinline__ half2 __shfl_xor(half2 var, int laneMask, int width) {
     typedef union half2_b32 {
@@ -261,4 +263,4 @@ static __device__ __forceinline__ half2 __shfl_xor(half2 var, int laneMask, int
     tmp.b32 = __shfl_xor(tmp.b32, laneMask, width);
     return tmp.val;
 }
-#endif // defined(__HIP_PLATFORM_AMD__) && HIP_VERSION < 50600000
+#endif // HIP_VERSION < 50600000