OMAP: HWMOD: Adding clockdomain check

This patch adds check for presence of clockdomain structure in the API
omap_hwmod_get_pwrdm before trying to access the powerdomain structure.
This will prevent unnecessary crashing of the system in case of a
clock node with out an associated clockdomain.
Signed-off-by: Thara Gopinath <thara@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>

arch/arm/mach-omap2/omap_hwmod.c

@@ -1511,6 +1511,9 @@ struct powerdomain *omap_hwmod_get_pwrdm(struct omap_hwmod *oh)
 		c = oh->slaves[oh->_mpu_port_index]->_clk;
 	}
 
+	if (!c->clkdm)
+		return NULL;
+
 	return c->clkdm->pwrdm.ptr;
 
 }