msm: iommu: Use clk_set_rate() instead of clk_set_min_rate()

Calling clk_set_min_rate() is no better than just calling
clk_set_rate() because MSM clock code already takes care of
calling the min_rate ops if the clock really needs
clk_set_min_rate() called on it.

Cc: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Joerg Roedel <joro@8bytes.org>
Signed-off-by: David Brown <davidb@codeaurora.org>