AMD K8 fam10-15: Tidy up CAR disable

Avoid conflicting disable_cache_as_ram() declaration and tidy
up include for inlined function.

Change-Id: Iba77c711f5eb023566b7d8ba148583948661bc99
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/20563
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/include/cpu/amd/car.h

@@ -9,10 +9,7 @@ void post_cache_as_ram(void);
 void cache_as_ram_switch_stack(void *stacktop);
 void cache_as_ram_new_stack(void);
 
-#if IS_ENABLED(CONFIG_CPU_AMD_AGESA) || IS_ENABLED(CONFIG_CPU_AMD_PI) || \
-	IS_ENABLED(CONFIG_SOC_AMD_PI)
 void disable_cache_as_ram(void);
-#endif
 
 void asmlinkage early_all_cores(void);