amd/stoneyridge: Consolidate duplicate comment

Change-Id: Ifaf8815dff595eb723f1b864b8f827768cb43847
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/22243
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/amd/stoneyridge/include/soc/southbridge.h

@@ -30,14 +30,10 @@
 #endif
 #define HPET_BASE_ADDRESS		0xfed00000
 
-/* Offsets from ACPI_MMIO_BASE */
+/* Register blocks at fixed offsets from FED8_0000h and enabled in PMx04[1] */
+
 #define APU_SMI_BASE			0xfed80200
 
-/*
- * Offsets from ACPI_MMIO_BASE
- * This is defined by AGESA, but we don't include AGESA headers to avoid
- * polluting the namespace.
- */
 #define PM_MMIO_BASE			0xfed80300
 
 #define APU_UART0_BASE			0xfedc6000