certs: unify duplicated cmd_extract_certs and improve the log

cmd_extract_certs is defined twice. Unify them.

The current log shows the input file $(2), which might be empty.
You cannot know what is being created from the log, "EXTRACT_CERTS".

Change the log to show the output file with better alignment.

[Before]

  EXTRACT_CERTS   certs/signing_key.pem
  CC      certs/system_keyring.o
  EXTRACT_CERTS
  AS      certs/system_certificates.o
  CC      certs/common.o
  CC      certs/blacklist.o
  EXTRACT_CERTS
  AS      certs/revocation_certificates.o

[After]

  CERT    certs/signing_key.x509
  CC      certs/system_keyring.o
  CERT    certs/x509_certificate_list
  AS      certs/system_certificates.o
  CC      certs/common.o
  CC      certs/blacklist.o
  CERT    certs/x509_revocation_list
  AS      certs/revocation_certificates.o
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>

certs/Makefile

@@ -12,6 +12,9 @@ else
 obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist_nohashes.o
 endif
 
+quiet_cmd_extract_certs  = CERT    $@
+      cmd_extract_certs  = scripts/extract-cert $(2) $@
+
 ifeq ($(CONFIG_SYSTEM_TRUSTED_KEYRING),y)
 
 $(eval $(call config_filename,SYSTEM_TRUSTED_KEYS))
@@ -22,9 +25,6 @@ $(obj)/system_certificates.o: $(obj)/x509_certificate_list
 # Cope with signing_key.x509 existing in $(srctree) not $(objtree)
 AFLAGS_system_certificates.o := -I$(srctree)
 
-quiet_cmd_extract_certs  = EXTRACT_CERTS   $(patsubst "%",%,$(2))
-      cmd_extract_certs  = scripts/extract-cert $(2) $@
-
 targets += x509_certificate_list
 $(obj)/x509_certificate_list: scripts/extract-cert $(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(SYSTEM_TRUSTED_KEYS_FILENAME) FORCE
 	$(call if_changed,extract_certs,$(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_TRUSTED_KEYS))
@@ -98,9 +98,6 @@ $(eval $(call config_filename,SYSTEM_REVOCATION_KEYS))
 
 $(obj)/revocation_certificates.o: $(obj)/x509_revocation_list
 
-quiet_cmd_extract_certs  = EXTRACT_CERTS   $(patsubst "%",%,$(2))
-      cmd_extract_certs  = scripts/extract-cert $(2) $@
-
 targets += x509_revocation_list
 $(obj)/x509_revocation_list: scripts/extract-cert $(SYSTEM_REVOCATION_KEYS_SRCPREFIX)$(SYSTEM_REVOCATION_KEYS_FILENAME) FORCE
 	$(call if_changed,extract_certs,$(SYSTEM_REVOCATION_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_REVOCATION_KEYS))