examples/fips_validation: fix build

examples/fips_validation: fix build

The example was not added to the Makefile and there are some
compilation errors:

examples/fips_validation/main.c: In function ‘prepare_aead_op’:
error: control reaches end of non-void function
examples/fips_validation/main.c: In function ‘prepare_auth_op’:
error: control reaches end of non-void function

Fixes: 3d0fad56b74a ("examples/fips_validation: add crypto FIPS application")
Fixes: f64adb6714e0 ("examples/fips_validation: support HMAC parsing")
Fixes: 4aaad2995e13 ("examples/fips_validation: support GCM parsing")

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
Tested-by: Ferruh Yigit <ferruh.yigit@intel.com>