soc: renesas: ra: configure option settings memory

An area of flash memory on the RA4M1 MCU is used to store information
used to configure the device following a reset. This patch instructs
the linker to reserve this memory area and provides kconfig options
that are used to populate it (at build time) with the desired device
configuration.

Signed-off-by: Ian Morris <ian.d.morris@outlook.com>