OMAP: powerdomain: Fix overflow when doing powerdomain deps lookups.

At the end of the list pd is a pointer to a NULL struct, so checking
if the address == NULL doesn't help here. In fact the original code
will just keep running past the struct to read who knows what in
memory.

This case manifests itself when from clkdms_setup() when enabling auto
idle for a clock domain and the clockdomain usecount is greater than
0. When _clkdm_add_autodeps() tries to add the a dependency that does
not exist in the powerdomain->wkdep_srcs array the for loop will run
past the wkdep_srcs array.

Currently in linux-omap you won't hit this because the not found case
is never executed, unless you start modifying powerdomains and their
wakeup/sleep deps.
Signed-off-by: Mike Chan <mike@android.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>

arch/arm/mach-omap2/powerdomain.c

@@ -83,7 +83,7 @@ static struct powerdomain *_pwrdm_deps_lookup(struct powerdomain *pwrdm,
 	if (!pwrdm || !deps || !omap_chip_is(pwrdm->omap_chip))
 		return ERR_PTR(-EINVAL);
 
-	for (pd = deps; pd; pd++) {
+	for (pd = deps; pd->pwrdm_name; pd++) {
 
 		if (!omap_chip_is(pd->omap_chip))
 			continue;
@@ -96,7 +96,7 @@ static struct powerdomain *_pwrdm_deps_lookup(struct powerdomain *pwrdm,
 
 	}
 
-	if (!pd)
+	if (!pd->pwrdm_name)
 		return ERR_PTR(-ENOENT);
 
 	return pd->pwrdm;