USB: hub: Clean up use of port initialization schemes and retries

USB: hub: Clean up use of port initialization schemes and retries

The SET_CONFIG_TRIES macro in hub.c is badly named; it controls the
number of port-initialization retry attempts rather than the number of
Set-Configuration attempts.  Furthermore, the USE_NEW_SCHEME macro and
use_new_scheme() function are written in a very confusing manner,
making it almost impossible to figure out exactly what they do or
check that they are correct.

This patch renames SET_CONFIG_TRIES to PORT_INIT_TRIES, removes
USE_NEW_SCHEME entirely, and rewrites use_new_scheme() to be much more
transparent, with added comments explaining how it works.  The patch
also pulls the single call site of use_new_scheme() out from the
Get-Descriptor retry loop (where it returns the same value each time)
and renames the local variable used to store the result.

The overall effect is a minor cleanup.  However, there is one
functional change: If the "use_both_schemes" module parameter isn't
set (by default it is set), the existing code does only two retry
iterations.  After this patch it will always perform four, regardless
of the parameter's value.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20200928152050.GA134701@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>