Input: usbtouchscreen - fix fallout caused by move from drivers/usb

During the move from drivers/usb/input into drivers/input/touchscreen
Kconfig variables were shuffled a bit to use a new namespace
(CONFIG_TOUCHSCREEN) while usbtouchscreen was still using old ones.

Also noticed by Robert P. J. Day <rpjday@mindspring.com>

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Daniel Ritz <daniel.ritz@gmx.ch>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>