can/esd_usb2: Rename esd_usb2.c to esd_usb.c

As suggested by Vincent, renaming of esd_usb2.c to esd_usb.c
and according to that, adaption of Kconfig and Makfile, too.

Link: https://lore.kernel.org/all/20220624190517.2299701-2-frank.jungclaus@esd.eu


Signed-off-by: Frank Jungclaus <frank.jungclaus@esd.eu>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>