clk: qcom: Don't overwrite 'cfg' in clk_rcg2_dfs_populate_freq()

The DFS frequency table logic overwrites 'cfg' while detecting the
parent clk and then later on in clk_rcg2_dfs_populate_freq() we use that
same variable to figure out the mode of the clk, either MND or not. Add
a new variable to hold the parent clk bit so that 'cfg' is left
untouched for use later.

This fixes problems in detecting the supported frequencies for any clks
in DFS mode.

Fixes: cc4f6944 ("clk: qcom: Add support for RCG to register for DFS")
Reported-by: Rajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lkml.kernel.org/r/20200128193329.45635-1-sboyd@kernel.org


Tested-by: Rajendra Nayak <rnayak@codeaurora.org>