[clang][RISCV] Reorder sema check for RVV type (#83553)

Currently using the command `clang -cc1 -triple riscv64` to compile the
code below:
```
#include <riscv_vector.h>
void foo() {
  vfloat64m1_t f64m1;
}
```
would get the error message "RISC-V type 'vfloat64m1_t' ... requires the
'zve64x' extension"
which is supposed to be "RISC-V type 'vfloat64m1_t' ... requires the
'zve64d' extension".