clk: sprd: return correct type of value for _sprd_pll_recalc_rate

The function _sprd_pll_recalc_rate() defines return value to unsigned
long, but it would return a negative value when malloc fail, changing
to return its parent_rate makes more sense, since if the callback
.recalc_rate() is not set, the framework returns the parent_rate as
well.

Fixes: 3e37b005 ("clk: sprd: add adjustable pll support")
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Link: https://lkml.kernel.org/r/20200519030036.1785-2-zhang.lyra@gmail.comReviewed-by: Baolin Wang <baolin.wang7@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/sprd/pll.c

@@ -106,7 +106,7 @@ static unsigned long _sprd_pll_recalc_rate(const struct sprd_pll *pll,
 
 	cfg = kcalloc(regs_num, sizeof(*cfg), GFP_KERNEL);
 	if (!cfg)
-		return -ENOMEM;
+		return parent_rate;
 
 	for (i = 0; i < regs_num; i++)
 		cfg[i] = sprd_pll_read(pll, i);