[PATCH] Minor bootflag.c fix

[Thomas Hood]

Without this patch, bootflag.c misleadingly reports an
invalid value read from CMOS RAM if SBF was not
enabled.

The patch:
--- linux-2.4.10-ac12/arch/i386/kernel/bootflag.c	Thu Oct 11 21:56:08 2001
+++ linux-2.4.10-ac12-fix/arch/i386/kernel/bootflag.c	Fri Oct 12 23:46:57 2001
@@ -128,7 +128,10 @@
 
 static void __init sbf_bootup(void)
 {
-	u8 v = sbf_read();
+	u8 v;
+	if(sbf_port == -1)
+		return;
+	v = sbf_read();
 	if(!sbf_value_valid(v))
 		printk(KERN_WARNING "SBF: Simple boot flag value 0x%x read from CMOS RAM was invalid\n",v);
 	v &= ~SBF_RESERVED;