ARM: keystone: Drop use of meminfo since its not available anymore

Laura's series removed the meminfo structure and its no longer available.
Update keystone code to remove the usage of it.

Reported-by: Russell King - ARM Linux <linux@arm.linux.org.uk>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>