[MTD] [MAPS] fix plat-ram printk format

drivers/mtd/maps/plat-ram.c:172: warning: format '%lx' expects type 'long unsigned int', but argument 4 has type 'resource_size_t'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>