kernel: allow building zsmalloc as a module again

zsmalloc was changed to a bool because of missing exports in the kernel,
but we already export the required symbol, so change it back to tristate.

Closes #13481.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>

SVN-Revision: 36587

target/linux/generic/patches-3.8/996-zsmalloc_allow_module_build.patch

@@ -0,0 +1,9 @@
+--- a/drivers/staging/zsmalloc/Kconfig
++++ b/drivers/staging/zsmalloc/Kconfig
+@@ -1,5 +1,5 @@
+ config ZSMALLOC
+-	bool "Memory allocator for compressed pages"
++	tristate "Memory allocator for compressed pages"
+ 	default n
+ 	help
+ 	  zsmalloc is a slab-based memory allocator designed to store

target/linux/generic/patches-3.9/996-zsmalloc_allow_module_build.patch

@@ -0,0 +1,9 @@
+--- a/drivers/staging/zsmalloc/Kconfig
++++ b/drivers/staging/zsmalloc/Kconfig
+@@ -1,5 +1,5 @@
+ config ZSMALLOC
+-	bool "Memory allocator for compressed pages"
++	tristate "Memory allocator for compressed pages"
+ 	default n
+ 	help
+ 	  zsmalloc is a slab-based memory allocator designed to store