[new uImage] Define a API for image handling operations

- Add inline helper macros for basic header processing
- Move common non inline code common/image.c
- Replace direct header access with the API routines
- Rename IH_CPU_* to IH_ARCH_*

Signed-off-by: Marian Balakowicz <m8@semihalf.com>
diff --git a/common/Makefile b/common/Makefile
index 533c415..d3a4a85 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -36,6 +36,7 @@
 COBJS-$(CONFIG_CMD_BDI) += cmd_bdinfo.o
 COBJS-$(CONFIG_CMD_BEDBUG) += cmd_bedbug.o
 COBJS-$(CONFIG_CMD_BMP) += cmd_bmp.o
+COBJS-y += image.o
 COBJS-y += cmd_boot.o
 COBJS-y += cmd_bootm.o
 COBJS-$(CONFIG_CMD_CACHE) += cmd_cache.o