clk: tegra: remove USB from clk init table

The USB clocks are just clock gates, so no need to set a specific clock.
In fact trying to set a specific clock is just a NOP if the requested
clockrate is the same as those of the parent (clk_m) or will trigger a
WARN_ON() if rates don't match up.

As we are not setting a specific rate, nor activating the clocks at
init, there is no point in keeping the the usb entries in the clock init
table.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Reviewed-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Olof Johansson <olof@lixom.net>