rtc: tegra: Drop MODULE_ALIAS

RTC driver was converted to OF driver long time ago. The MODULE_ALIAS
macro has no effect for the OF drivers since the alias is overridden by
the drivers core to follow the OF naming convention of the driver's alias,
which is based on the device-tree matching name.

$ cat /sys/devices/soc0/7000e000.rtc/modalias
of:NrtcT(null)Cnvidia,tegra20-rtc

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>