ARCMWDT: Remove workaround with stripping DWARF info

Remove obsolete workaround with conditional turning off "-g"
flag when Thread Local Storage used.

Recent versions of MetaWare have no issue with linking files with
TSL-related data.

Moreover, pointed workaround breaks userspace for recently added
ARC-V platforms, as they use both TLS and DWARF info while compilation
process.

Fixes https://github.com/zephyrproject-rtos/zephyr/issues/29920



Signed-off-by: Nikolay Agishev <agishev@synopsys.com>