intel: Use MSR_EBC_FREQUENCY_ID instead of 0x2c

Change-Id: Ib1b761fc417f1bb000f408d3bed5e8666963f51d
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/22603
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Martin Roth <martinroth@google.com>

src/mainboard/asus/p5gc-mx/romstage.c

@@ -94,7 +94,7 @@ static u8 msr_get_fsb(void)
 
 	/* Netburst */
 	if (((eax >> 8) & 0xf) == 0xf) {
-		msr = rdmsr(0x2c);
+		msr = rdmsr(MSR_EBC_FREQUENCY_ID);
 		fsbcfg = (msr.lo >> 16) & 0x7;
 	} else { /* Intel Core 2 */
 		msr = rdmsr(MSR_FSB_FREQ);