Replace flash partitioning terminology

This change replaces the slot 0/1 terminology with primary/secondary
slot and replaces FLASH_AREA_IMAGE_0/1 with
FLASH_AREA_IMAGE_PRIMARY/SECONDARY. This naming convention may be more
understandable, fits better to MCUs with multiple images and it is an
architecture agnostic alternative as well.

Change-Id: I655a585f6ae023852c671ee6635399efe25209c9
Signed-off-by: David Vincze <david.vincze@arm.com>
Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/boot/zephyr/include/sysflash/sysflash.h b/boot/zephyr/include/sysflash/sysflash.h
index 0fef026..2492244 100644
--- a/boot/zephyr/include/sysflash/sysflash.h
+++ b/boot/zephyr/include/sysflash/sysflash.h
@@ -5,8 +5,8 @@
 
 #include <generated_dts_board.h>
 
-#define FLASH_AREA_IMAGE_0 DT_FLASH_AREA_IMAGE_0_ID
-#define FLASH_AREA_IMAGE_1 DT_FLASH_AREA_IMAGE_1_ID
-#define FLASH_AREA_IMAGE_SCRATCH DT_FLASH_AREA_IMAGE_SCRATCH_ID
+#define FLASH_AREA_IMAGE_PRIMARY    DT_FLASH_AREA_IMAGE_0_ID
+#define FLASH_AREA_IMAGE_SECONDARY  DT_FLASH_AREA_IMAGE_1_ID
+#define FLASH_AREA_IMAGE_SCRATCH    DT_FLASH_AREA_IMAGE_SCRATCH_ID
 
 #endif /* __SYSFLASH_H__ */