hw/intc/loongson_ipi: Access memory in little endian

hw/intc/loongson_ipi: Access memory in little endian

Loongson IPI is only available in little-endian,
so use that to access the guest memory (in case
we run on a big-endian host).

Cc: qemu-stable@nongnu.org
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Fixes: f6783e3438 ("hw/loongarch: Add LoongArch ipi interrupt support")
[PMD: Extracted from bigger commit, added commit description]
Co-Developed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Tested-by: Bibo Mao <maobibo@loongson.cn>
Acked-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Tested-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-Id: <20240718133312.10324-3-philmd@linaro.org>
(cherry picked from commit 2465c89fb983eed670007742bd68c7d91b6d6f85)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: fixups for 9.0, for lack of:
 v9.0.0-583-g91d0b151de4c "hw/intc/loongson_ipi: Implement IOCSR address space for MIPS"
 v9.0.0-582-gb4a12dfc2132 "hw/intc/loongarch_ipi: Rename as loongson_ipi")