Drop ROMCC code and header guards

Change-Id: I730f80afd8aad250f26534435aec24bea75a849c
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37334
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
diff --git a/src/include/cpu/amd/mtrr.h b/src/include/cpu/amd/mtrr.h
index edbf7bb..906a7c0 100644
--- a/src/include/cpu/amd/mtrr.h
+++ b/src/include/cpu/amd/mtrr.h
@@ -38,7 +38,7 @@
 #define TOP_MEM_MASK			0x007fffff
 #define TOP_MEM_MASK_KB			(TOP_MEM_MASK >> 10)
 
-#if !defined(__ROMCC__) && !defined(__ASSEMBLER__)
+#if !defined(__ASSEMBLER__)
 
 #include <cpu/x86/msr.h>