Rename 'module' to 'kmodule' in ARM-specific code

To keep pace with common code.

Signed-off-by: Junjie Mao <eternal.n08@gmail.com>
Provide a correct way to add default ARCH

The most preferred ARCH value should be read from config file. The
default value should only take effect when config file is missing.

Signed-off-by: Junjie Mao <eternal.n08@gmail.com>