For consistency with the naming of (most) other documentation files for DT
bindings for Renesas IP blocks rename the Renesas USB3.0 peripheral
documentation file from renesas,usb3.txt to renesas,usb3-peri.txt

This refines a recent rename from renesas_usb3.txt to renesas,usb3.txt.
The motivation is to more accurately reflect the IP block documented in
this file.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Sderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20190809213710.31783-1-horms+renesas@verge.net.auSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>