The omap_mmc_reset() function resets its SD card via
device_legacy_reset().  We know that the SD card does not have a qbus
of its own, so the new device_cold_reset() function (which resets
both the device and its child buses) is equivalent here to
device_legacy_reset() and we can just switch to the new API.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20210430222348.8514-1-peter.maydell@linaro.org