ARM: EXYNOS: Handle of_find_device_by_node() and kstrdup() failures

Prevent possible NULL pointer dereference of pointer returned by
of_find_device_by_node(). Handle this by skipping such power domain.

Additionally fail the init on kstrdup() failure. Such case is actually
not fatal because the name for power domain allocated by kstrdup() is
used only in printk. Still as a precaution handle this as an error
condition.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>