target-tricore: Add FPU infrastructure

This patch adds a file for all the FPU related helpers with all the includes,
useful defines, and a function to update the status bits. Additionally it adds
a mask for the rounding mode bits of PSW as well as all the opcodes for the
FPU instructions.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Message-Id: <1457708597-3025-2-git-send-email-kbastian@mail.uni-paderborn.de>