include/cpu/x86/msr: fix MCG_CTL_P definition

MCG_CTL_P is bit 8 of the IA32_MCG_CAP MSR and not bit 3. Bits 0-7 of
that MSR contain the number of MCA banks being present on the CPU. At
the moment this definition of MCG_CTL_P is unused.

Change-Id: I39a59083daa5c2db11a8074d5c4881bf55688f43
Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56179
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/include/cpu/x86/msr.h

@@ -36,7 +36,7 @@
 #define SMBASE_RO_MSR			0x98
 #define  IA32_SMM_MONITOR_VALID		(1 << 0)
 #define IA32_MCG_CAP			0x179
-#define  MCG_CTL_P			(1 << 3)
+#define  MCG_CTL_P			(1 << 8)
 #define  MCA_BANKS_MASK			0xff
 #define IA32_PERF_STATUS		0x198
 #define IA32_PERF_CTL			0x199