Platform/Loongson: Support vga for loongarch.

Add VGA graphics card support for Loongarch,
VGA graphics cards have GOP to support early
kernel information printing, so we need it.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Bibo Mao <maobibo@loongson.cn>
Cc: Chao Li <lichao@loongson.cn>
Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Signed-off-by: xianglai li <lixianglai@loongson.cn>
Reviewed-by: Chao Li <lichao@loongson.cn>