mm: Kconfig: fixup zsmalloc configuration

zsmalloc is not exclusive to zswap.  Commit b3fbd58 ("mm: Kconfig:
simplify zswap configuration") made CONFIG_ZSMALLOC only visible when
CONFIG_ZSWAP is selected, which makes it impossible to menuconfig
zsmalloc-specific features (stats, chain-size, etc.) on systems that use
ZRAM but don't have ZSWAP enabled.

Make zsmalloc depend on both ZRAM and ZSWAP.

Link: https://lkml.kernel.org/r/20240903040143.1580705-1-senozhatsky@chromium.org
Fixes: b3fbd58 ("mm: Kconfig: simplify zswap configuration") 
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/Kconfig

@@ -188,7 +188,7 @@ config Z3FOLD
 
 config ZSMALLOC
 	tristate
-	prompt "N:1 compression allocator (zsmalloc)" if ZSWAP
+	prompt "N:1 compression allocator (zsmalloc)" if (ZSWAP || ZRAM)
 	depends on MMU
 	help
 	  zsmalloc is a slab-based memory allocator designed to store