slimbus: remove redundant dev_err message

devm_ioremap_resource already contains error message, so remove
the redundant dev_err message

Signed-off-by: Ding Xiang <dingxiang@cmss.chinamobile.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>