RISC-V: Clean up the pr106602.c testcase
The test case that was added is rv64i-specific, as there's better ways
to generate this code on rv32i (where the long/int cast is a NOP) and on
rv64i_zba (where we have word shifts). This renames the original test
case and adds two more for those targets.
gcc/testsuite/ChangeLog:
PR target/106602
* gcc.target/riscv/pr106602.c: Moved to...
* gcc.target/riscv/pr106602-rv64i.c: ...here.
* gcc.target/riscv/pr106602-rv32i.c: New test.
* gcc.target/riscv/pr106602-rv64i_zba.c: New test.
(cherry picked from commit
8c010f6fe5ebe80d2e054b31e04ae0e9f12ae368)