x86: Address gcc4.6 "set but not used" warnings in apic.h

native_apic_msr_read() and x2apic_enabled() use rdmsr(msr, low, high),
but only use the low part.

gcc4.6 complains about this:
.../apic.h:144:11: warning: variable 'high' set but not used [-Wunused-but-set-variable]

rdmsr() is just a wrapper around rdmsrl() which splits the 64bit value
into low and high, so using rdmsrl() directly solves this.

[tglx: Changed the variables to u64 as suggested by Cyrill. It's less
       confusing and has no code impact as this is 64bit only anyway.
       Massaged changelog as well. ]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: x86@kernel.org
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
LKML-Reference: <1289251229-19589-1-git-send-email-andi@firstfloor.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/include/asm/apic.h

@@ -141,13 +141,13 @@ static inline void native_apic_msr_write(u32 reg, u32 v)
 
 static inline u32 native_apic_msr_read(u32 reg)
 {
-	u32 low, high;
+	u64 msr;
 
 	if (reg == APIC_DFR)
 		return -1;
 
-	rdmsr(APIC_BASE_MSR + (reg >> 4), low, high);
-	return low;
+	rdmsrl(APIC_BASE_MSR + (reg >> 4), msr);
+	return (u32)msr;
 }
 
 static inline void native_x2apic_wait_icr_idle(void)
@@ -181,12 +181,12 @@ extern void enable_x2apic(void);
 extern void x2apic_icr_write(u32 low, u32 id);
 static inline int x2apic_enabled(void)
 {
-	int msr, msr2;
+	u64 msr;
 
 	if (!cpu_has_x2apic)
 		return 0;
 
-	rdmsr(MSR_IA32_APICBASE, msr, msr2);
+	rdmsrl(MSR_IA32_APICBASE, msr);
 	if (msr & X2APIC_ENABLE)
 		return 1;
 	return 0;