drivers/ide: make ide-scan-pci.c driver explicitly non-modular

The Kconfig for this support is currently:

config IDEPCI_PCIBUS_ORDER
        bool "Probe IDE PCI devices in the PCI bus order (DEPRECATED)"

...meaning that it currently is not being built as a module by anyone.
Lets change the initcall to be the equivalent device_initcall, so that
when reading the driver code, there is no doubt it is builtin-only.

Unlike other similar changes, we leave the module.h header to be
included since this code interacts with other drivers and needs to
know what a struct module is.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-ide@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>