bimgtool: Drop unused targets and variables from Makefile

dep has not been defined (and will hence break the build)
LDFLAGS is not used.

Change-Id: I4f91e1e7a176367aa4e1a1c63a2afc0b3186767e
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: https://review.coreboot.org/13653
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

util/bimgtool/Makefile

@@ -6,9 +6,8 @@ CFLAGS += -D_7ZIP_ST
 CFLAGS += -Wall -Wundef -Wstrict-prototypes -Wmissing-prototypes
 CFLAGS += -Wwrite-strings -Wredundant-decls -Wno-trigraphs
 CFLAGS += -Wstrict-aliasing -Wshadow -Werror
-LDFLAGS += -g
 
-all: dep $(obj)/bimgtool
+all: $(obj)/bimgtool
 
 clean:
 	rm -f $(obj)/bimgtool