soc: qcom: geni: Don't ignore clk_round_rate() errors in geni_se_clk_tbl_get()

The function clk_round_rate() is defined to return a "long", not an
"unsigned long".  That's because it might return a negative error
code.  Change the call in geni_se_clk_tbl_get() to check for errors.

While we're at it, get rid of a useless init of "freq".

NOTE: overall the idea that we should iterate over clk_round_rate() to
try to reconstruct a table already present in the clock driver is
questionable.  Specifically:
- This method relies on "clk_round_rate()" rounding up.
- This method only works if the table is sorted and has no duplicates.
...this patch doesn't try to fix those problems, it just makes the
error handling more correct.

Fixes: eddac5af ("soc: qcom: Add GENI based QUP Wrapper driver")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>