[U-Boot] [PATCH v5 1/3] common: Move bootm_decomp_image() to image.c (as image_decomp())

[Julius Werner]

> I'd like to review this, but maybe you can help me speed up the process and tell
> us if the move has been a 1:1 code move or if you had to adapt things to the new
> location (other than the function being renamed)?

print_decomp_msg() is a 1:1 move. bootm_decomp_image() is mostly 1:1
move, except that I changed the return code for unimplemented
compression type (from BOOTM_ERR_UNIMPLEMENTED to -ENOSYS) and removed
the call to handle_decomp_error() (handle_decomp_error() is specific
to the BOOTM_ERR error types which are only used within bootm.c, so I
decoupled it from image_decomp() and made all the call sites in
bootm.c call it explicitly).