clk: qcom: smd-rpm: use msm8998_ln_bb_clk2 for qcm2290 SoC

The qcm2290's ln_bb_clk2 is identical to the freshly added msm8998's
ln_bb_clk2 one. Use the latter and drop the SoC-specific version.

Reviewed-by: Alex Elder <elder@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221209164855.128798-7-dmitry.baryshkov@linaro.org