tcg: Move TCG_TYPE_TL from tcg.h to tcg-op.h

tcg: Move TCG_TYPE_TL from tcg.h to tcg-op.h

Removes the only use of TARGET_LONG_BITS from tcg.h, which is to be
target independent.  Move the symbol to a define in tcg-op.h, which
will continue to be target dependent.  Rather than complicate matters
for the use in tb_gen_code(), expand the definition there.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>