hw/loongarch/virt: Fix memory leak

hw/loongarch/virt: Fix memory leak

The char pointer 'ramName' point to a block of memory,
but never free it. Use 'g_autofree' to automatically free it.

Resolves: Coverity CID 1544773

Fixes: 0cf1478d6 ("hw/loongarch: Add numa support")
Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240507022239.3113987-1-gaosong@loongson.cn>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
(cherry picked from commit 54c52ec719fb8c83bbde54cb87b58688ab27c166)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: context fixup in hw/loongarch/virt.c due to missing-in-8.2
      v9.0.0-266-gd771ca1c10 "hw/loongarch: Move boot functions to boot.c")