staging: comedi: addi_apci_1564: move addi_watchdog.h include to addi_apci_1564.c

Commit aed3f9d4 (staging: comedi: addi_apci_1564: absorb apci1564_reset()) moved
the only use of addi_watchdog.h from hwdrv_apci1564.c to addi_apci_1564.c, but
left the include statement itself in the former file.  Move this include to the
file which actually uses it.

Signed-off-by: Chase Southwood <chase.southwood@gmail.com>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk.>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>