lib: crypto: add pkcs7 message parser

Imported from linux kernel v5.3:
 pkcs7.asn1 without changes
 pkcs7.h with changes marked as __UBOOT__
 pkcs7_parser.h without changes
 pkcs7_parser.c with changes marked as __UBOOT__

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
index d7e27be..8267fee 100644
--- a/lib/crypto/Makefile
+++ b/lib/crypto/Makefile
@@ -36,3 +36,14 @@
 
 $(obj)/x509.asn1.o: $(obj)/x509.asn1.c $(obj)/x509.asn1.h
 $(obj)/x509_akid.asn1.o: $(obj)/x509_akid.asn1.c $(obj)/x509_akid.asn1.h
+
+#
+# PKCS#7 message handling
+#
+obj-$(CONFIG_PKCS7_MESSAGE_PARSER) += pkcs7_message.o
+pkcs7_message-y := \
+	pkcs7.asn1.o \
+	pkcs7_parser.o
+
+$(obj)/pkcs7_parser.o: $(obj)/pkcs7.asn1.h
+$(obj)/pkcs7.asn1.o: $(obj)/pkcs7.asn1.c $(obj)/pkcs7.asn1.h