[clang][driver] Do not emit default '-Tdata' for AVR devices

[clang][driver] Do not emit default '-Tdata' for AVR devices

Different AVR devices have different data regions. Current clang
driver emits a default '-Tdata' option to the linker. This way
works fine if there is no user specified linker script, but it
will cause conflicts if there is one.

A better solution for setting the default data region to GNU ld
is defining symbol __DATA_REGION_ORIGIN__, which is expected by
GNU ld's default AVR linker script.

Fixes https://github.com/llvm/llvm-project/issues/60362

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D144533