wireless: replace usage of hexdump with od/sed

Since od/sed are in posix, hopefully there's a better chance
people will have them, over hexdump.

Fixes: 90a53e44 ("cfg80211: implement regdb signature checking")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/Makefile

@@ -27,7 +27,7 @@ $(obj)/shipped-certs.c: $(wildcard $(srctree)/$(src)/certs/*.x509)
 	@$(kecho) "  GEN     $@"
 	@echo '#include "reg.h"' > $@
 	@echo 'const u8 shipped_regdb_certs[] = {' >> $@
-	@for f in $^ ; do hexdump -v -e '1/1 "0x%.2x," "\n"' < $$f >> $@ ; done
+	@for f in $^ ; do od -An -v -tx1 < $$f | sed -e 's/ /\n/g' | sed -e 's/^[0-9a-f]\+$$/\0/;t;d' | sed -e 's/^/0x/;s/$$/,/' >> $@ ; done
 	@echo '};' >> $@
 	@echo 'unsigned int shipped_regdb_certs_len = sizeof(shipped_regdb_certs);' >> $@
 
@@ -36,6 +36,6 @@ $(obj)/extra-certs.c: $(CONFIG_CFG80211_EXTRA_REGDB_KEYDIR:"%"=%) \
 	@$(kecho) "  GEN     $@"
 	@echo '#include "reg.h"' > $@
 	@echo 'const u8 extra_regdb_certs[] = {' >> $@
-	@for f in $^ ; do test -f $$f && hexdump -v -e '1/1 "0x%.2x," "\n"' < $$f >> $@ || true ; done
+	@for f in $^ ; do test -f $$f && od -An -v -tx1 < $$f | sed -e 's/ /\n/g' | sed -e 's/^[0-9a-f]\+$$/\0/;t;d' | sed -e 's/^/0x/;s/$$/,/' >> $@ ; done
 	@echo '};' >> $@
 	@echo 'unsigned int extra_regdb_certs_len = sizeof(extra_regdb_certs);' >> $@