net: stmmac: tegra: Properly allocate clock bulk data

The clock data is an array of struct clk_bulk_data, so make sure to
allocate enough memory.

Fixes: d8ca1137 ("net: stmmac: tegra: Add MGBE support")
Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>