kernel/ixp4xx: update config for v6.18

The new symbol CONFIG_PAGE_BLOCK_MAX_ORDER typical value
for ARM is 9 (2MB) so set this.

Link: openwrt/openwrt#22896
Signed-off-by: Linus Walleij <linusw@kernel.org>

Author: linusw

target/linux/ixp4xx/config-6.18

@@ -189,6 +189,7 @@ CONFIG_OF_KOBJ=y
 CONFIG_OF_MDIO=y
 CONFIG_OLD_SIGACTION=y
 CONFIG_OLD_SIGSUSPEND3=y
+CONFIG_PAGE_BLOCK_MAX_ORDER=9
 CONFIG_PAGE_OFFSET=0xC0000000
 CONFIG_PAGE_POOL=y
 CONFIG_PAGE_SIZE_LESS_THAN_256KB=y