xtensa: clean up boot make rules

- remove duplicate rules for binary and packed image
- use predefined macros for ld/objcopy/gzip
- remove build-id section from bootable elf image

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
3 files changed