SMC: Fix compiler warnings

security/smc/tf_device.c:174: missing braces around initializer
security/smc/tf_device.c:174: (near initialization for 'g_tf_dev.kobj')

Change-Id: Ia8b3b9420ab3b860900d1db9fe0ed925b96fc200
Signed-off-by: Bryan Buckley <bryan.buckley@ti.com>