tests/tcg/loongarch64: Use --no-warn-rwx-segments to link system tests

tests/tcg/loongarch64: Use --no-warn-rwx-segments to link system tests

Recent debian cross-linker for loongarch issues

  ld: warning: hello has a LOAD segment with RWX permissions

This is partially related to tests/tcg/loongarch64/system/kernel.ld,
but is not fixed by explicitly adding a single LOAD PHDR.
Disable the warning, since it does not apply to kernel images.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20240724010733.22129-3-richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240729144414.830369-5-alex.bennee@linaro.org>