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: cc4f6944d0 ("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>

drivers/clk/qcom/clk-rcg2.c

@@ -953,7 +953,7 @@ static void clk_rcg2_dfs_populate_freq(struct clk_hw *hw, unsigned int l,
 	struct clk_rcg2 *rcg = to_clk_rcg2(hw);
 	struct clk_hw *p;
 	unsigned long prate = 0;
-	u32 val, mask, cfg, mode;
+	u32 val, mask, cfg, mode, src;
 	int i, num_parents;
 
 	regmap_read(rcg->clkr.regmap, rcg->cmd_rcgr + SE_PERF_DFSR(l), &cfg);
@@ -963,12 +963,12 @@ static void clk_rcg2_dfs_populate_freq(struct clk_hw *hw, unsigned int l,
 	if (cfg & mask)
 		f->pre_div = cfg & mask;
 
-	cfg &= CFG_SRC_SEL_MASK;
+	src = cfg & CFG_SRC_SEL_MASK;
-	cfg >>= CFG_SRC_SEL_SHIFT;
+	src >>= CFG_SRC_SEL_SHIFT;
 
 	num_parents = clk_hw_get_num_parents(hw);
 	for (i = 0; i < num_parents; i++) {
-		if (cfg == rcg->parent_map[i].cfg) {
+		if (src == rcg->parent_map[i].cfg) {
 			f->src = rcg->parent_map[i].src;
 			p = clk_hw_get_parent_by_index(&rcg->clkr.hw, i);
 			prate = clk_hw_get_rate(p);