Support rv32 ULEB128 test

Use opcodes available to both rv32 and rv64 in uleb128 module linking
test.

Fixes: af71bc19 ("riscv: Add tests for riscv module loading")
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Closes: https://lore.kernel.org/lkml/1d7c71ee-5742-4df4-b8ef-a2aea0a624eb@infradead.org/
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Link: https://lore.kernel.org/r/20231122-module_fixup-v2-1-dfb9565e9ea5@rivosinc.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>