armsr: armv8: enable serial console for Renesas platforms

armsr: armv8: enable serial console for Renesas platforms

Support for Renesas Arm families was added in commit 1ff4f4df2301
("armsr: armv8: enable CONFIG_ARCH_RENESAS"), but this did not
enable the console/tty hardware for these SoCs, which is derived
from the SuperH family (CONFIG_SERIAL_SH_SCI).

Link: https://github.com/openwrt/openwrt/issues/15284
Signed-off-by: Mathew McBride <matt@traverse.com.au>
(cherry picked from commit 683355d0a6d51cbeda258492bc16a9c6413b387e)
Link: https://github.com/openwrt/openwrt/pull/15808
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>