target/mips: Move sysemu TCG-specific code to tcg/sysemu/ subfolder

Move cp0_helper.c and mips-semi.c to the new tcg/sysemu/ folder,
adapting the Meson machinery.

Move the opcode definitions to tcg/sysemu_helper.h.inc.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210428170410.479308-20-f4bug@amsat.org>
7 files changed