Some boards use secure monitor calls to communicate with secure
firmware.

This patch adds exynos_smc function which uses smc assembly instruction
to do secure monitor calls.
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NTomasz Figa <t.figa@samsung.com>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>