Enable edonr in FreeBSD

The code is integrated, builds fine, runs fine, there's not really
any reason not to.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #12735

include/sys/zio.h

@@ -88,9 +88,7 @@ enum zio_checksum {
 	ZIO_CHECKSUM_NOPARITY,
 	ZIO_CHECKSUM_SHA512,
 	ZIO_CHECKSUM_SKEIN,
-#if !defined(__FreeBSD__)
 	ZIO_CHECKSUM_EDONR,
-#endif
 	ZIO_CHECKSUM_FUNCTIONS
 };