tty: serial: samsung: make max_count unsigned int

``max_count`` negative values are not used. Since ``port->fifosize``
is an unsigned int, make ``max_count`` the same.
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://lore.kernel.org/r/20240119104526.1221243-13-tudor.ambarus@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/samsung_tty.c

@@ -760,8 +760,8 @@ static irqreturn_t s3c24xx_serial_rx_chars_dma(void *dev_id)
 static void s3c24xx_serial_rx_drain_fifo(struct s3c24xx_uart_port *ourport)
 {
 	struct uart_port *port = &ourport->port;
+	unsigned int max_count = port->fifosize;
 	unsigned int fifocnt = 0;
-	int max_count = port->fifosize;
 	u32 ufcon, ufstat, uerstat;
 	u8 ch, flag;