spi: SPISG: Fix less than zero comparison on a u32 variable

The check for ns < 0 is always false because variable ns is a u32 which
is not a signed type. Fix this by making ns a s32 type.

Fixes: cef9991 ("spi: Add Amlogic SPISG driver")
Signed-off-by: Colin Ian King <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: ColinIanKing

drivers/spi/spi-amlogic-spisg.c

@@ -163,7 +163,7 @@ struct spisg_device {
 
 static int spi_delay_to_sclk(u32 slck_speed_hz, struct spi_delay *delay)
 {
-	u32 ns;
+	s32 ns;
 
 	if (!delay)
 		return 0;