integrity: digital signature config option name change

Similar to SIGNATURE, rename INTEGRITY_DIGSIG to INTEGRITY_SIGNATURE.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/integrity/Makefile b/security/integrity/Makefile
index bece056..d43799c 100644
--- a/security/integrity/Makefile
+++ b/security/integrity/Makefile
@@ -3,7 +3,7 @@
 #
 
 obj-$(CONFIG_INTEGRITY) += integrity.o
-obj-$(CONFIG_INTEGRITY_DIGSIG) += digsig.o
+obj-$(CONFIG_INTEGRITY_SIGNATURE) += digsig.o
 
 integrity-y := iint.o