This patch adds Big Endian architecture support. Even if a compiler
generating big endian object files is used, our linker script, or
include/linker/linker-tool-gcc.h to be precise, has default output
format as little endian.
This patch adds a hidden config CONFIG_BIG_ENDIAN, which should be set
by big endian architectures or a SoC's, and adds an condition to
switch OUTPUT_FORMAT in our linker.cmd.
Signed-off-by: Yasushi SHOJI <y-shoji@ispace-inc.com>