[SCSI] aic7xxx, aic79xx: deinline functions

Deinlines and moves big functions from .h to .c files.
Adds prototypes for ahc_lookup_scb and ahd_lookup_scb to .h files.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>