ARM: dra762: Enable SMP for dra762

smp specific routines are called based on soc_is_*() api in omap-smc.c.
Add soc_is_dra76x() to the condition so that smp specific routines are
called for dra76 SoC.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>