clk: qcom: Allocate space for NULL terimation in DFS table

The table allocated in clk_rcg2_dfs_populate_freq_table() is
eventually iterated over by qcom_find_freq() which assumes that the
table is NULL terminated.  Allocate one extra space in the array for
the NULL termination.  Initting of the NULL termination is implicit
due to kcalloc().

Fixes: cc4f6944 ("clk: qcom: Add support for RCG to register for DFS")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>