tty: serial: fsl_lpuart: Fix unused variable 'sport' build warning

Remove the unused variable 'sport' to avoid the kernel build warning.

Fixes: 3cc16ae ("tty: serial: fsl_lpuart: use port struct directly to simply code")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202503210614.2qGlnbIq-lkp@intel.com/
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20250324021051.162676-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: SherrySun5

drivers/tty/serial/fsl_lpuart.c

@@ -639,8 +639,6 @@ static void lpuart32_wait_bit_set(struct uart_port *port, unsigned int offset,
 
 static int lpuart_poll_init(struct uart_port *port)
 {
-	struct lpuart_port *sport = container_of(port,
-					struct lpuart_port, port);
 	unsigned long flags;
 	u8 fifo;
 
@@ -693,7 +691,6 @@ static int lpuart_poll_get_char(struct uart_port *port)
 static int lpuart32_poll_init(struct uart_port *port)
 {
 	unsigned long flags;
-	struct lpuart_port *sport = container_of(port, struct lpuart_port, port);
 	u32 fifo;
 
 	port->fifosize = 0;