clean-up: Remove the no more necessary ENV_HAS_DATA_SECTION flag

With commit b7832de026 ("x86: Add .data
section support for pre-memory stages"), the `ENV_HAS_DATA_SECTION'
flag and its derivatives can now be removed from the code.

Change-Id: Ic0afac76264a9bd4a9c93ca35c90bd84e9b747a2
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/77291
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Maximilian Brune <maximilian.brune@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/rules.h

@@ -278,9 +278,6 @@
 #define ENV_CACHE_AS_RAM		0
 #endif
 
-/* Indicates .data section support. */
-#define ENV_HAS_DATA_SECTION		1
-
 /* Indicates if the stage uses the _data and _bss regions defined in
  * arch/x86/car.ld */
 #define ENV_SEPARATE_DATA_AND_BSS	(ENV_CACHE_AS_RAM && (ENV_BOOTBLOCK || !CONFIG(NO_XIP_EARLY_STAGES)))

src/include/stddef.h

@@ -34,12 +34,6 @@ typedef __WINT_TYPE__ wint_t;
 #define DEVTREE_CONST
 #endif
 
-#if ENV_HAS_DATA_SECTION
-#define MAYBE_STATIC_NONZERO static
-#else
-#define MAYBE_STATIC_NONZERO
-#endif
-
 /* Provide a pointer to address 0 that thwarts any "accessing this is
  * undefined behaviour and do whatever" trickery in compilers.
  * Use when you _really_ need to read32(zeroptr) (ie. read address 0).