generic: 5.15: add missing PAGE_POOL_STATS config

Add new PAGE_POOL_STATS config backported for the mtk offload patches.

Signed-off-by: Christian Marangi <[email protected]>

target/linux/generic/config-5.15

@@ -4463,6 +4463,7 @@ CONFIG_PACKET=y
 # CONFIG_PAGE_EXTENSION is not set
 # CONFIG_PAGE_OWNER is not set
 # CONFIG_PAGE_POISONING is not set
+# CONFIG_PAGE_POOL_STATS is not set
 # CONFIG_PAGE_REPORTING is not set
 # CONFIG_PAGE_SIZE_16KB is not set
 # CONFIG_PAGE_SIZE_32KB is not set