USB: rename USB OTG hub configuration option

USB: rename USB OTG hub configuration option

The USB OTG code has the ability to disable external hubs, but the
configuration option for it is oddly named.  Rename it to be more
obvious as to what it does.

Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Bin Liu <b-liu@ti.com>
Cc: Paul Cercueil <paul@crapouillou.net>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Eugeniu Rosca <erosca@de.adit-jv.com>
Cc: Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc: David Heinzelmann <heinzelmann.david@gmail.com>
Cc: "Lee, Chiasheng" <chiasheng.lee@intel.com>
Cc: Keiya Nobuta <nobuta.keiya@fujitsu.com>
Cc: Hardik Gajjar <hgajjar@de.adit-jv.com>
Link: https://lore.kernel.org/r/20200618094300.1887727-3-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>