[Ada] Remove disabled code

[Pierre-Marie de Rodat]

This old code is likely made obsolete by recent changes related to the
handling of the universal access "=" operator.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* sem_attr.adb (Resolve_Attribute): Remove dead code.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: patch.diff
Type: text/x-diff
Size: 935 bytes
Desc: not available
URL: <https://gcc.gnu.org/pipermail/gcc-patches/attachments/20200727/73d6062d/attachment-0001.bin>