regulator: qcom_spmi: Fix calculating number of voltages

n /= range->step_uV + 1; is equivalent to n /= (range->step_uV + 1);
which is wrong. Fix it.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Mark Brown <broonie@kernel.org>