Fix #2103: qemu/target/ppc/mem_helper.c remove redundant returns

[disconnect3d]

This fixes the issue described in #2103 - compilation errors when building Unicorn Engine:

/build/unicorn-2.1.2/src/qemu/target/ppc/mem_helper.c: In function ‘helper_stq_le_parallel’:
/build/unicorn-2.1.2/src/qemu/target/ppc/mem_helper.c:423:12: error: ‘return’ with a value, in function returning void [-Wreturn-mismatch]
  423 |     return 0;
      |            ^
/build/unicorn-2.1.2/src/qemu/target/ppc/mem_helper.c: In function ‘helper_stq_be_parallel’:
/build/unicorn-2.1.2/src/qemu/target/ppc/mem_helper.c:439:12: error: ‘return’ with a value, in function returning void [-Wreturn-mismatch]
  439 |     return 0;
      |            ^

As pointed by @patryk4815

Since GCC 14, the -Wreturn-mismatch warning has been promoted to an error by default (as mentioned here).

[wtdcode]

Oh… this was introduced by me when refactoring the related code😱

[wtdcode]

Thanks!

[patryk4815]

Oh… this was introduced by me when refactoring the related code😱