clk: qcom: Constify struct freq_tbl

'struct freq_tbl' are not modified in these drivers.

Constifying this structure moves some data to a read-only section, so
increase overall security.

On a x86_64, with allmodconfig, as an example:
Before:
======
   text	   data	    bss	    dec	    hex	filename
   7595	  43696	      0	  51291	   c85b	drivers/clk/qcom/mmcc-apq8084.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
   9867	  41424	      0	  51291	   c85b	drivers/clk/qcom/mmcc-apq8084.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/e8aee66fa83a4e65f7e855eb8bdbc91275d6994b.1720962107.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Bjorn Andersson <andersson@kernel.org>