firmware: arm_scpi: Prevent the ternary sign expansion bug

stable inclusion
from linux-4.19.192
commit dcbce0b6f38476b380a0dec28e237d9398ca2bfe

--------------------------------

[ Upstream commit d9cd78ed ]

How the type promotion works in ternary expressions is a bit tricky.
The problem is that scpi_clk_get_val() returns longs, "ret" is a int
which holds a negative error code, and le32_to_cpu() is an unsigned int.
We want the negative error code to be cast to a negative long.  But
because le32_to_cpu() is an u32 then "ret" is type promoted to u32 and
becomes a high positive and then it is promoted to long and it is still
a high positive value.

Fix this by getting rid of the ternary.

Link: https://lore.kernel.org/r/YIE7pdqV/h10tEAK@mwanda
Fixes: 8cb7cf56 ("firmware: add support for ARM System Control and Power Interface(SCPI) protocol")
Reviewed-by: NCristian Marussi <cristian.marussi@arm.com>
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
[sudeep.holla: changed to return 0 as clock rate on error]
Signed-off-by: NSudeep Holla <sudeep.holla@arm.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/firmware/arm_scpi.c

@@ -563,8 +563,10 @@ static unsigned long scpi_clk_get_val(u16 clk_id)
 
 	ret = scpi_send_message(CMD_GET_CLOCK_VALUE, &le_clk_id,
 				sizeof(le_clk_id), &rate, sizeof(rate));
+	if (ret)
+		return 0;
 
-	return ret ? ret : le32_to_cpu(rate);
+	return le32_to_cpu(rate);
 }
 
 static int scpi_clk_set_val(u16 clk_id, unsigned long rate)