openssl: build kmods only if engines are selected

Add a conditional to the individual package's for the kmods in DEPENDS.
This avoids the need to compile the kernel modules when the crypto
engine packages are not selected.  The final binares are not affected by
this.

Signed-off-by: Eneas U de Queiroz <cote2004-github@yahoo.com>
Tested-by: Rosen Penev <rosenp@gmail.com>

package/libs/openssl/Makefile

@@ -139,8 +139,8 @@ define Package/libopenssl-afalg
   $(call Package/openssl/Default)
   SUBMENU:=SSL
   TITLE:=AFALG hardware acceleration engine
-  DEPENDS:=libopenssl @OPENSSL_ENGINE @KERNEL_AIO @!LINUX_3_18 +kmod-crypto-user \
-	   +libopenssl-conf @!OPENSSL_ENGINE_BUILTIN
+  DEPENDS:=libopenssl @OPENSSL_ENGINE @KERNEL_AIO @!LINUX_3_18 \
+	   +PACKAGE_libopenssl-afalg:kmod-crypto-user +libopenssl-conf @!OPENSSL_ENGINE_BUILTIN
 endef
 
 define Package/libopenssl-afalg/description
@@ -156,7 +156,7 @@ define Package/libopenssl-devcrypto
   $(call Package/openssl/Default)
   SUBMENU:=SSL
   TITLE:=/dev/crypto hardware acceleration engine
-  DEPENDS:=libopenssl @OPENSSL_ENGINE +kmod-cryptodev +libopenssl-conf \
+  DEPENDS:=libopenssl @OPENSSL_ENGINE +PACKAGE_libopenssl-devcrypto:kmod-cryptodev +libopenssl-conf \
 	   @!OPENSSL_ENGINE_BUILTIN
 endef
 
@@ -173,7 +173,7 @@ define Package/libopenssl-padlock
   $(call Package/openssl/Default)
   SUBMENU:=SSL
   TITLE:=VIA Padlock hardware acceleration engine
-  DEPENDS:=libopenssl @OPENSSL_ENGINE @TARGET_x86 +kmod-crypto-hw-padlock \
+  DEPENDS:=libopenssl @OPENSSL_ENGINE @TARGET_x86 +PACKAGE_libopenssl-padlock:kmod-crypto-hw-padlock \
 	   +libopenssl-conf @!OPENSSL_ENGINE_BUILTIN
 endef