Merge tag 'usb-serial-5.12-rc1' of https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial into usb-next

Johan writes:

USB-serial updates for 5.12-rc1

Here are the USB-serial updates for 5.12-rc1, including:

 - a line-speed fix for newer pl2303 devices
 - a line-speed fix for FTDI FT-X devices
 - a new xr_serial driver for MaxLinear/Exar devices (non-ACM mode)
 - a cdc-acm blacklist entry for when the xr_serial driver is enabled
 - cp210x support for software flow control
 - various cp210x modem-control fixes
 - an updated ZTE P685M modem entry to stop claiming the QMI interface
 - an update to drop the port_remove() driver-callback return value

Included are also various clean ups.

All have been in linux-next with no reported issues.

* tag 'usb-serial-5.12-rc1' of https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial: (41 commits)
  USB: serial: drop bogus to_usb_serial_port() checks
  USB: serial: make remove callback return void
  USB: serial: drop if with an always false condition
  USB: serial: option: update interface mapping for ZTE P685M
  USB: serial: ftdi_sio: restore divisor-encoding comments
  USB: serial: ftdi_sio: fix FTX sub-integer prescaler
  USB: serial: cp210x: clean up auto-RTS handling
  USB: serial: cp210x: fix RTS handling
  USB: serial: cp210x: clean up printk zero padding
  USB: serial: cp210x: clean up flow-control debug message
  USB: serial: cp210x: drop shift macros
  USB: serial: cp210x: fix modem-control handling
  USB: serial: cp210x: suppress modem-control errors
  USB: serial: mos7720: fix error code in mos7720_write()
  USB: serial: xr: fix B0 handling
  USB: serial: xr: fix pin configuration
  USB: serial: xr: fix gpio-mode handling
  USB: serial: xr: simplify line-speed logic
  USB: serial: xr: clean up line-settings handling
  USB: serial: xr: document vendor-request recipient
  ...