module_param: check type correctness for module_param_array

module_param_array(), unlike its non-array cousins, didn't check the type
of the variable.  Fixing this found two bugs.

Cc: Luca Risolia <luca.risolia@studio.unibo.it>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Eric Piel <eric.piel@tremplin-utc.net>
Cc: linux-media@vger.kernel.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>