riscv: give -mcmodel=medany to GCC when linking
riscv: give -mcmodel=medany to GCC when linking

We compile objects with -mcmodel=medany. Now also give -mcmodel=medany
to the GCC front-end when linking to pick up the corresponding
multilibs.

Signed-off-by: Martin Åberg <37424e7fbe3f8590d57db5ed6ae5b8866742b6be@gaisler.com>

galak/zephyr,finikorg/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr,nashif/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,nashif/zephyr