target/i386: TCG supports RDSEED

TCG implements RDSEED, and in fact uses qcrypto_random_bytes which is
secure enough to match hardware behavior.  Expose it to guests.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/i386/cpu.c

@@ -657,11 +657,10 @@ void x86_cpu_vendor_words2str(char *dst, uint32_t vendor1,
           CPUID_7_0_EBX_BMI1 | CPUID_7_0_EBX_BMI2 | CPUID_7_0_EBX_ADX | \
           CPUID_7_0_EBX_PCOMMIT | CPUID_7_0_EBX_CLFLUSHOPT |            \
           CPUID_7_0_EBX_CLWB | CPUID_7_0_EBX_MPX | CPUID_7_0_EBX_FSGSBASE | \
-          CPUID_7_0_EBX_ERMS | CPUID_7_0_EBX_AVX2)
+          CPUID_7_0_EBX_ERMS | CPUID_7_0_EBX_AVX2 | CPUID_7_0_EBX_RDSEED)
           /* missing:
           CPUID_7_0_EBX_HLE
-          CPUID_7_0_EBX_INVPCID, CPUID_7_0_EBX_RTM,
-          CPUID_7_0_EBX_RDSEED */
+          CPUID_7_0_EBX_INVPCID, CPUID_7_0_EBX_RTM */
 #define TCG_7_0_ECX_FEATURES (CPUID_7_0_ECX_UMIP | CPUID_7_0_ECX_PKU | \
           /* CPUID_7_0_ECX_OSPKE is dynamic */ \
           CPUID_7_0_ECX_LA57 | CPUID_7_0_ECX_PKS | CPUID_7_0_ECX_VAES)