qla2xxx: Remove decrement of sp reference count in abort handler.

Fix for memory leak when command is not found by firmware due to
mismatch in sp reference count.

Signed-off-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>