ath9k: add loader for AR92XX (and older) pci(e)

ath9k: add loader for AR92XX (and older) pci(e)

Atheros cards with a AR92XX generation (and older) chip usually
store their pci(e) initialization vectors on an external eeprom chip.
However these chips technically don't need the eeprom chip attached,
the AR9280 Datasheet in section "6.1.2 DEVICE_ID" describes that
"... if the EEPROM content is not valid, a value of 0xFF1C returns
when read from the register". So, they will show up on the system's
pci bus. However in that state, ath9k can't load, since it relies
on having the correct pci-id, otherwise it doesn't know what chip it
actually is. This happens on many embedded devices like routers
and accesspoint since they want to keep the BOM low and store the
pci(e) initialization vectors together with the calibration data
on the system's FLASH, which is out of reach of the ath9k chip.

Furthermore, Some devices (like the Cisco Meraki Z1 Cloud Managed
Teleworker Gateway) need to be able to initialize the PCIe wifi device.
Normally, this should be done as a pci quirk during the early stages of
booting linux. However, this isn't possible for devices which have the
init code for the Atheros chip stored on NAND in an UBI volume.
Hence, this module can be used to initialize the chip when the
user-space is ready to extract the init code.

Martin Blumenstingl prodived the following fixes:
owl-loader: add support for OWL emulation PCI devices
owl-loader: don't re-scan the bus when ath9k_pci_fixup failed
owl-loader: use dev_* instead of pr_* logging functions
owl-loader: auto-generate the eeprom filename as fallback
owl-loader: add a debug message when swapping the eeprom data
owl-loader: add missing newlines in log messages

Reviewed-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>