clk: tegra: fix error return case for recalc_rate

tegra-bpmp clocks driver makes implicit conversion of signed error
code to unsigned value in recalc_rate operation. The behavior for
recalc_rate, according to it's specification, should be that "If the
driver cannot figure out a rate for this clock, it must return 0."

Fixes: ca6f2796eef7 ("clk: tegra: Add BPMP clock driver")
Signed-off-by: Timo Alho <[e-mail]>
Signed-off-by: Mikko Perttunen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/tegra/clk-bpmp.c

···
 
 	err = tegra_bpmp_clk_transfer(clk->bpmp, &msg);
 	if (err < 0)
-		return err;
+		return 0;
 
 	return response.rate;
 }