scsi: aic7xxx: fix firmware build deps

We need to override Kbuild rules for copying shipped files, otherwise
aic7xxx_reg.h and aic7xxx_reg_print.c will be ovewritten by old versions.

Fixes: 516b7db5


Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>