cbfstool: Clean up code

cbfstool has diverged between coreboot upstream and the chromium tree.
Bring in some of the chromium changes, in particular the useful remainders
of cbf37fe (https://chromium-review.googlesource.com/176710)

- fix coding style
- mark unused variables explicitly unused
- remove some dead code

Change-Id: I354aaede8ce425ebe99d4c60c232feea62bf8a11
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/8577
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>

util/cbfstool/cbfs.h

@@ -125,7 +125,6 @@ struct cbfs_payload {
 #define CBFS_SUBHEADER(_p) ( (void *) ((((uint8_t *) (_p)) + ntohl((_p)->offset))) )
 /* cbfs_image.c */
 uint32_t get_cbfs_entry_type(const char *name, uint32_t default_value);
-const char *get_cbfs_entry_type_name(uint32_t type);
 uint32_t get_cbfs_compression(const char *name, uint32_t unknown);
 
 /* common.c */