staging: cxt1e1: fix sbeCrc function declaration

This patch fixes the following sparse warning:

drivers/staging/cxt1e1/sbecrc.c:86:1: warning: symbol 'sbeCrc' was not declared. Should it be static?

Furthermore it fixes wring sbeCrc return type in function declaration.

Signed-off-by: Pawel Lebioda <pawel.lebioda89@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>