Staging: iio: Aditional fixpoint formatted output bugfix

iio: Additional fixpoint formatted output bugfixes

Fix some ADC/DAC drivers' _scale interface to correct fixpoint formatted output

This patch adds the fixes to ad7887_core.c and ad5446.c

Signed-off-by: Roland Stigge <stigge@antcom.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>