staging: wilc1000: remove linux version checks

For code that is integrated into mainline Linux, checks for
the kernel version make no sense, because we know which version
we are compiling against.

This removes all checks and the associated dead code.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>