samsung: common: do not reset if cros-ec uclass is missing

Otherwise non-ChromeOS samsung devices, like the odroid boards, are
stuck in a bootloop if CONFIG_CROS_EC is not enabled:

    <...>
    MMC: SAMSUNG SDHCI: 2, EXYNOS DWMMC: 0
    Loading Environment from MMC... *** Warning - bad CRC, using default environment

    cros-ec communications failure -96

    Please reset with Power+Refresh

    Cannot init cros-ec device
    resetting ...

Issue started after commit e44d7e73 ("dm: core: Switch
uclass_*_device_err to use uclass_*_device_check").

Signed-off-by: Henrik Grimler <henrik@grimler.se>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Minkyu Kang <mk7.kang@samsung.com>