serial: max3100: Fix bitwise types

Sparse is not happy about misuse of bitwise types:

  .../max3100.c:194:13: warning: incorrect type in assignment (different base types)
  .../max3100.c:194:13:    expected unsigned short [addressable] [usertype] etx
  .../max3100.c:194:13:    got restricted __be16 [usertype]
  .../max3100.c:202:15: warning: cast to restricted __be16

Fix this by choosing proper types for the respective variables.

Fixes: 7831d56b ("tty: MAX3100")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240402195306.269276-4-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/max3100.c

@@ -45,6 +45,9 @@
 #include <linux/freezer.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
+#include <linux/types.h>
+
+#include <asm/unaligned.h>
 
 #include <linux/serial_max3100.h>
 
@@ -191,7 +194,7 @@ static void max3100_timeout(struct timer_list *t)
 static int max3100_sr(struct max3100_port *s, u16 tx, u16 *rx)
 {
 	struct spi_message message;
-	u16 etx, erx;
+	__be16 etx, erx;
 	int status;
 	struct spi_transfer tran = {
 		.tx_buf = &etx,