clk: qcom: smd-rpm: remove duplication between MMXI and MMAXI defines

The commit 644c4229 ("clk: qcom: smd: Add SM6375 clocks") added a
duplicate of the existing define QCOM_SMD_RPM_MMAXI_CLK, drop it now.

Fixes: 644c4229 ("clk: qcom: smd: Add SM6375 clocks")
Reviewed-by: Alex Elder <elder@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/20221209164855.128798-4-dmitry.baryshkov@linaro.org