clk: tegra: remove non-existent clocks

The Tegra124 clock driver currently provides 3 clocks that don't actually
exist; 2 for NAND and one for UART5/UARTE. Delete these.

Cc: <stable@vger.kernel.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>