soc: renesas: rz: Fix loader program

Due to a change in linker script cortex_a_r/scripts/linker.ld
, the _image_ram_start has been changed so the Zephyr image
cannot be copied from flash to ram as expected
and cannot run properly.
It is replaced by CONFIG_SRAM_BASE_ADDRESS, the _image_ram_size is also
replaced by _flash_used as a preventive measure.

Signed-off-by: Nhut Nguyen <nhut.nguyen.kc@renesas.com>
1 file changed