target-tricore: Move general CHECK_REG_PAIR of decode_rrr_divide

The add.f and sub.f to be implemented don't use 64 bit registers
and a general usage of CHECK_REG_PAIR would always generate an
exception for them.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Message-Id: <1457708597-3025-3-git-send-email-kbastian@mail.uni-paderborn.de>
