amd64: Check cpu_vendor instead of using CPUID.

[Christiano F. Haesbaert]

There's no need for doing that somewhat strange comparison, the rest
of the code already uses cpu_vendor. 

ok ?

Index: identcpu.c
===================================================================
RCS file: /cvs/src/sys/arch/amd64/amd64/identcpu.c,v
retrieving revision 1.35
diff -d -u -p -r1.35 identcpu.c
--- identcpu.c  27 Mar 2012 02:23:04 -0000      1.35
+++ identcpu.c  22 Apr 2012 12:59:10 -0000
@@ -302,7 +302,6 @@ identifycpu(struct cpu_info *ci)
        u_int64_t last_tsc;
        u_int32_t dummy, val, pnfeatset;
        u_int32_t brand[12];
-       u_int32_t vendor[4];
        char mycpu_model[48];
        int i, max;
        char *brandstr_from, *brandstr_to;
@@ -433,11 +432,7 @@ identifycpu(struct cpu_info *ci)
 
 #endif
 
-       vendor[3] = 0;
-       CPUID(0, dummy, vendor[0], vendor[2], vendor[1]);       /* yup, 0 2 1 */
-       /* AuthenticAMD:    h t u A                    i t n e */
-       if (vendor[0] == 0x68747541 && vendor[1] == 0x69746e65 &&
-           vendor[2] == 0x444d4163)    /* DMAc */
+       if (!strcmp(cpu_vendor, "AuthenticAMD"))
                amd64_errata(ci);
 
        if (strncmp(mycpu_model, "VIA Nano processor", 18) == 0) {