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: d37010a3c162 ("clk: ls1028a: Add clock driver for Display output interface")
Signed-off-by: Colin Ian King <[e-mail]>
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/clk-plldig.c

···
 {
 	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;
 
 	if (!parent)
 		return -EINVAL;
+
+	parent_rate = clk_hw_get_rate(parent);
 
 	if (data->vco_freq) {
 		mfd = data->vco_freq / parent_rate;