[mlir][sparse] Improving the FATAL macro

The previous macro definition using `{...}` would fail to compile when the callsite uses a semicolon followed by an else-statement (i.e., `if (...) FATAL(...); else ...;`).  Replacing the simple braces with `do{...}while(0)` (n.b., semicolon not included in the macro definition) enables callsites to use the semicolon plus else-statement syntax without problems.  The new definition now requires the semicolon at all callsites, but since it was already being called that way nothing changes.

For more explanation, see <https://gcc.gnu.org/onlinedocs/cpp/Swallowing-the-Semicolon.html>

Reviewed By: aartbik

Differential Revision: https://reviews.llvm.org/D126514