sparc64: simplify boot()

[Miod Vallat]

Although Open Firmware supports it, there is no way from OpenBSD to
reboot with a specified boot command line, so drop vestigial support for
it from boot().

Index: sparc64/machdep.c
===================================================================
RCS file: /OpenBSD/src/sys/arch/sparc64/sparc64/machdep.c,v
retrieving revision 1.191
diff -u -p -r1.191 machdep.c
--- sparc64/machdep.c   1 Apr 2019 07:00:52 -0000       1.191
+++ sparc64/machdep.c   3 Jan 2020 19:24:45 -0000
@@ -593,9 +593,6 @@ struct pcb dumppcb;
 __dead void
 boot(int howto)
 {
-       int i;
-       static char str[128];
-
        if ((howto & RB_RESET) != 0)
                goto doreset;
 
@@ -655,30 +652,7 @@ haltsys:
 
 doreset:
        printf("rebooting\n\n");
-#if 0
-       if (user_boot_string && *user_boot_string) {
-               i = strlen(user_boot_string);
-               if (i > sizeof(str))
-                       OF_boot(user_boot_string);      /* XXX */
-               bcopy(user_boot_string, str, i);
-       } else
-#endif
-       {
-               i = 1;
-               str[0] = '\0';
-       }
-
-       if ((howto & RB_SINGLE) != 0)
-               str[i++] = 's';
-       if ((howto & RB_KDB) != 0)
-               str[i++] = 'd';
-       if (i > 1) {
-               if (str[0] == '\0')
-                       str[0] = '-';
-               str[i] = 0;
-       } else
-               str[0] = 0;
-       OF_boot(str);
+       OF_boot("");
        panic("cpu_reboot -- failed");
        for (;;)
                continue;