riscv64: correct comparison logic of have_fast_v

Change-Id: I47fdc0900a8edf878e99a57d6f06ff6e12ca74f2
Signed-off-by: Kenny Gong <kenny.gong@intel.com>
diff --git a/libc/arch-riscv64/dynamic_function_dispatch.cpp b/libc/arch-riscv64/dynamic_function_dispatch.cpp
index 24fafe7..265ce3e 100644
--- a/libc/arch-riscv64/dynamic_function_dispatch.cpp
+++ b/libc/arch-riscv64/dynamic_function_dispatch.cpp
@@ -48,7 +48,7 @@
   static bool result = []() {
     // We don't want to do a full "bogomips" test, so just check for the
     // presence of a file that would indicate that we're running in qemu.
-    return ifunc_faccessat(AT_FDCWD, "/dev/hvc0", F_OK) == 0;
+    return ifunc_faccessat(AT_FDCWD, "/dev/hvc0", F_OK) != 0;
   }();
   return result;
 }