Correct the usage conditions of the macro RISCV_SIMD.

Signed-off-by: tingbo.liao <tingbo.liao@starfivetech.com>

common_riscv64.h

@@ -91,8 +91,10 @@ static inline int blas_quickdivide(blasint x, blasint y){
 
 #if defined(C910V) || defined(RISCV64_ZVL256B) || defined(RISCV64_ZVL128B) || defined(x280)
 # include <riscv_vector.h>
+#if defined(x280)
 #define RISCV_SIMD
 #endif
+#endif
 
 #if defined( __riscv_xtheadc ) && defined( __riscv_v ) && ( __riscv_v <= 7000 )
 // t-head toolchain uses obsolete rvv intrinsics, can't build for C910V without this