Input: sur40 - fix bad endianness handling in sur40_poll

sparse says:

  sur40.c:372:40: warning: restricted __le32 degrades to integer

the header's data is __le32 so we need to convert it before comparing.

Signed-off-by: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>