arc: Make TLS Local Dynamic work like Global Dynamic model

arc: Make TLS Local Dynamic work like Global Dynamic model

Current ARC's TLS Local Dynamic model is using two anchors to access
data, namely `.tdata` and `.tbss`. This implementation is unnecessary
complicated. However, the TLS Local Dynamic model has better results
using Global Dynamic model and anchors.

gcc/ChangeLog;

	* config/arc/arc.cc (arc_call_tls_get_addr): Simplify access using
	TLS Local Dynamic.

Signed-off-by: Claudiu Zissulescu <claziss@gmail.com>