target/sh4: do not use a helper to implement fneg

There is no need to use a helper to flip one bit, just use a TCG xor
instruction instead.

Message-Id: <20170702202814.27793-5-aurelien@aurel32.net>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
3 files changed