crypto: doc - remove crypto API DocBook

With the conversion of the documentation to Sphinx, the old DocBook is
now stale.
Signed-off-by: NStephan Mueller <smueller@chronox.de>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/DocBook/Makefile

@@ -13,7 +13,7 @@ DOCBOOKS := z8530book.xml  \
 	    gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
 	    genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \
 	    80211.xml sh.xml regulator.xml w1.xml \
-	    writing_musb_glue_layer.xml crypto-API.xml iio.xml
+	    writing_musb_glue_layer.xml iio.xml
 
 ifeq ($(DOCBOOKS),)