BACKPORT: usb: dwc3: core: Access XHCI address space temporarily to read port info

All DWC3 Multi Port controllers that exist today only support host mode.
Temporarily map XHCI address space for host-only controllers and parse
XHCI Extended Capabilities registers to read number of usb2 ports and
usb3 ports present on multiport controller. Each USB Port is at least HS
capable.

The port info for usb2 and usb3 phy are identified as num_usb2_ports
and num_usb3_ports and these are used as iterators for phy operations
and for modifying GUSB2PHYCFG/ GUSB3PIPECTL registers accordingly.

Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
Reviewed-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20240420044901.884098-3-quic_kriskura@quicinc.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 233985973
Change-Id: I918ec194e477bde071e7d11e8610a893594bfdf6
(cherry picked from commit 921e109c)
[Krishna: Resolved conflicts during backport]
Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>