cmake: linker: arm: memory regions from devicetree added

This commit add devicetree memory regions added to arm/linker.cmake.

The following memory regions are now added to the generated linker
script and scatter file if they exists in the devicetree.
- chosen:    zephyr,itcm
- chosen:    zephyr,dtcm
- nodelabel: ti_ccfg_partition
- nodelabel: sram1
- nodelabel: sram2
- nodelabel: sram3
- nodelabel: sram4
- nodelabel: sdram1
- nodelabel: sdram2
- nodelabel: backup_sram

Also support for the itcm and dtcm section and their placement in
corresponding memory regions has been added.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>