rules.h: Use more consistent naming

Use 'ENV' consistently and drop the redundant 'STAGE' in the naming.

Change-Id: I51f2a7e70eefad12aa214e92f23e5fd2edf46698
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64296
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

src/ec/acpi/ec.c

@@ -142,7 +142,7 @@ void ec_clr_bit(u8 addr, u8 bit)
 
 void ec_set_ports(u16 cmd_reg, u16 data_reg)
 {
-	if (!ENV_STAGE_HAS_DATA_SECTION)
+	if (!ENV_HAS_DATA_SECTION)
 		return;
 
 	ec_cmd_reg = cmd_reg;