ARM: dts: bockw: SCIF0 supports RTS/CTS hardware flow control

On the BOCK-W development board, the RTS and CTS pins of the console
SCIF0 are wired to the "product serial" connector.  Reflect this in the
DTS by adding the "uart-has-rtscts" property to the scif0 device node.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>