soc/intel/skylake: Move UNCORE PRMRR base and mask defines.

UNCORE PRMRR BASE and MASK MSRs are not common, so move to
SOC specific header file and rename the #define to start with MSR_*

Change-Id: I799c43f0b7a9eec5b3b69ab0f5100935c7f3f170
Signed-off-by: Pratik Prajapati <pratikkumar.v.prajapati@intel.com>
Reviewed-on: https://review.coreboot.org/21247
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/skylake/systemagent.c

@@ -69,9 +69,9 @@ int soc_get_uncore_prmmr_base_and_mask(uint64_t *prmrr_base,
 	uint64_t *prmrr_mask)
 {
 	msr_t msr;
-	msr = rdmsr(UNCORE_PRMRR_PHYS_BASE_MSR);
+	msr = rdmsr(MSR_UNCORE_PRMRR_PHYS_BASE);
 	*prmrr_base = (uint64_t) msr.hi << 32 | msr.lo;
-	msr = rdmsr(UNCORE_PRMRR_PHYS_MASK_MSR);
+	msr = rdmsr(MSR_UNCORE_PRMRR_PHYS_MASK);
 	*prmrr_mask = (uint64_t) msr.hi << 32 | msr.lo;
 	return 0;
 }