of/platform: sparse fix

drivers/of/platform.c:110:59: warning: incorrect type in argument 2 (different base types)
drivers/of/platform.c:110:59:    expected restricted __be32 const [usertype] *addr
drivers/of/platform.c:110:59:    got unsigned int const [usertype] *[assigned] reg

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>