drivers/intel/wifi: Change to PCI driver only

Currently, drivers/intel/wifi is a PCI driver (provides `struct
pci_driver`) as well as a chip driver (provids `struct
chip_operations`). However, there is no need for a separate chip driver
for the WiFi device since drivers/wifi/generic already provides one.

Having two separate chip drivers makes it difficult to multi-source
WiFi devices and share the same firmware target without having to add
a probe property for each of these devices. This is unnecessary since
the WiFi driver in coreboot is primarily responsible for:
1. PCI resource allocation
2. ACPI SSDT node generation to expose wake property and SAR tables
3. SMBIOS table generation

For the most part, coreboot can perform the above operations without
really caring about the specifics of which WiFi device is being used
by the mainboard. Thus, this change drops the chip driver from
drivers/intel/wifi and retains only the PCI driver. The PCI driver is
retained for backward compatibility with boards that never utilized
the chip driver to support Intel WiFi device. For these devices, the
PCI driver helps perform the same operations as above (except exposing
the wake property) by utilizing the same `wifi_generic_ops` exposed by
drivers/wifi/generic.

BUG=b:169802515
BRANCH=zork

Change-Id: I780a7d1a87f387d5e01e6b35aac7cca31a2033ac
Signed-off-by: Furquan Shaikh <furquan@google.com>
---
D src/drivers/intel/wifi/chip.h
M src/drivers/intel/wifi/wifi.c
2 files changed, 3 insertions(+), 95 deletions(-)