kernel: kmod-zram: break the strict dependency from lz4

Zram is only strictly dependent on lzo, not lz4. Break this dependency and
make the lz4 module visible in the configuration, in order for the user to
have the choice of enabling/disabling it, if (s)he sees fit.

Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>

package/kernel/linux/modules/lib.mk

@@ -147,7 +147,6 @@ define KernelPackage/lib-lz4
   SUBMENU:=$(LIB_MENU)
   TITLE:=LZ4 support
   DEPENDS:=+!LINUX_4_9:kmod-crypto-acompress
-  HIDDEN:=1
   KCONFIG:= \
 	CONFIG_CRYPTO_LZ4@ge4.9 \
 	CONFIG_LZ4_COMPRESS \

package/kernel/linux/modules/other.mk

@@ -899,15 +899,14 @@ $(eval $(call KernelPackage,ikconfig))
 define KernelPackage/zram
   SUBMENU:=$(OTHER_MENU)
   TITLE:=ZRAM
-  DEPENDS:=+kmod-lib-lzo +kmod-lib-lz4
+  DEPENDS:=+kmod-lib-lzo
   KCONFIG:= \
 	CONFIG_ZSMALLOC \
 	CONFIG_ZRAM \
 	CONFIG_ZRAM_DEBUG=n \
 	CONFIG_PGTABLE_MAPPING=n \
 	CONFIG_ZRAM_WRITEBACK=n \
-	CONFIG_ZSMALLOC_STAT=n \
-	CONFIG_ZRAM_LZ4_COMPRESS=y
+	CONFIG_ZSMALLOC_STAT=n
   FILES:= \
 	$(LINUX_DIR)/mm/zsmalloc.ko \
 	$(LINUX_DIR)/drivers/block/zram/zram.ko