w64: Change data type of parameters for flush_icache_range

The TCG targets i386 and tci needed a change of the function
prototype for w64.

This change is currently not needed for the other TCG targets,
but it can be applied to avoid code differences.

Cc: Blue Swirl <blauwirbel@gmail.com>
Cc: Andrzej Zaborowski <balrogg@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Alexander Graf <agraf@suse.de>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>