linker: arc: add .rodata_in_data section to avoid unexpected placement

The .rodata_in_data section is produced by MWDT toolchain with -Hccm
option enabled. This option moves read-only data from the executable
memory (ICCM) to the data memory (DCCM), improving performance by
reducing conflicts between instruction fetches and data fetches.

Signed-off-by: Ilya Tagunov <Ilya.Tagunov@synopsys.com>