include: Create linker for RX architecture

Add intial support for RX linker script
The RX GCC toolchain automatically adding an "_" as prefix
on every C symbol to comply to the arch ABI, for the C file
to understand the symbol define in linker script the
PLACE_SYMBOL_HERE() macro help to add "_" to linker script
define symbol if build with CONFIG_RX enable
This commit adding minimal support in common linker script
for RX arch

Signed-off-by: Duy Nguyen <duy.nguyen.xa@renesas.com>