clk: ls1028a: fix a dereference of pointer 'parent' before a null check

Currently the pointer 'parent' is being dereferenced before it is
being null checked. Fix this by performing the null check before
it is dereferenced.

Addresses-Coverity: ("Dereference before null check")
Fixes: d37010a3c1 ("clk: ls1028a: Add clock driver for Display output interface")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lkml.kernel.org/r/20200203223736.99645-1-colin.king@canonical.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/clk-plldig.c

@@ -187,7 +187,7 @@ static int plldig_init(struct clk_hw *hw)
 {
 	struct clk_plldig *data = to_clk_plldig(hw);
 	struct clk_hw *parent = clk_hw_get_parent(hw);
-	unsigned long parent_rate = clk_hw_get_rate(parent);
+	unsigned long parent_rate;
 	unsigned long val;
 	unsigned long long lltmp;
 	unsigned int mfd, fracdiv = 0;
@@ -195,6 +195,8 @@ static int plldig_init(struct clk_hw *hw)
 	if (!parent)
 		return -EINVAL;
 
+	parent_rate = clk_hw_get_rate(parent);
+
 	if (data->vco_freq) {
 		mfd = data->vco_freq / parent_rate;
 		lltmp = data->vco_freq % parent_rate;