hsi: controllers:remove redundant code

Use devm_ioremap_resource() in order to make the code simpler,
and remove redundant return value check of platform_get_resource()
because this value is alreadytaken care by devm_ioremap_resource()

Signed-off-by: Sanjeev Sharma <sanjeev_sharma@mentor.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>