usb: dwc3: qcom: Remove extcon functionality from glue layer

usb: dwc3: qcom: Remove extcon functionality from glue layer

Historically Qualcomm DWC3 glue driver supported both extcon and
usb-role-switch kinds of notifications. When Bjorn contributed [1] the
flattened representation for the DWC3 host controller, he also kept both
extcon and usb-role-switch support in the flattened driver & bindings.

Currently there are no in-kernel users for flattened DWC3 and extcon. As
device's DT needs to be manually converted from legacy to the flat DWC3
representation, we can drop (legacy / deprecated) extcon support from
the new DWC3 glue driver, significantly simplifying the code.

This potentially affects flattening effort for the following platforms:

Platforms currently using linux,extcon-usb-gpio device that need to
switch to gpio-usb-b-connector:
- apq8096-db820c,
- msm8996-sony-xperia-tone-dora

Platforms currently using linux,extcon-usb-gpio device that need to
switch to gpio-usb-c-connector (not supported at this moment) or to
implement typec support
- msm8996-sony-xperia-tone-kagura
- msm8996-sony-xperia-tone-keyaki
- msm8998-fxtec-pro1
- msm8998-sony-xperia-yoshino-lilac
- msm8998-sony-xperia-yoshino-maple
- msm8998-sony-xperia-yoshino-poplar
- sda660-inforce-ifc6560
- sdm630-sony-xperia-nile-discovery
- sdm630-sony-xperia-nile-pioneer
- sdm630-sony-xperia-nile-voyager
- sdm660-xiaomi-lavender
- sm6125-sony-xperia-seine-pdx201
- sm6125-xiaomi-ginkgo
- sm6125-xiaomi-laurel-sprout

Platforms using TI TUSB320L chip need to switch to represent the USB-C
connector properly (and to have a typec-class driver for the TUSB320L
chip):
- msm8996-xiaomi-gemini
- msm8996pro-xiaomi-natrium
- msm8996pro-xiaomi-scoprpio

Commit message suggested by Dmitry Baryshkov.

[1]: https://lore.kernel.org/all/20250414-dwc3-refactor-v7-0-f015b358722d@oss.qualcomm.com/

Signed-off-by: Krishna Kurapati <krishna.kurapati@oss.qualcomm.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250729092708.3628187-1-krishna.kurapati@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>