Replace ENV_RAMSTAGE with ENV_PAYLOAD_LOADER

This patch relying on new rule, ENV_PAYLOAD_LOADER which is set
to ENV_RAMSTAGE.

This approach will help to add future optimization (rampayload) in
coreboot flow if required.

Change-Id: Ib54ece7b9e5f281f8a092dc6f38c07406edfa5fa
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32725
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: ron minnich <rminnich@gmail.com>

src/include/stddef.h

@@ -23,7 +23,7 @@ typedef unsigned int wint_t;
 
 /* The devicetree data structures are only mutable in ramstage. All other
    stages have a constant devicetree. */
-#if !ENV_RAMSTAGE
+#if !ENV_PAYLOAD_LOADER
 #define DEVTREE_EARLY 1
 #else
 #define DEVTREE_EARLY 0