amdgpu/pm: Replace vega12,20 usage of sprintf with sysfs_emit

=== Test ===
AMDGPU_PCI_ADDR=`lspci -nn | grep "VGA\|Display" | cut -d " " -f 1`
AMDGPU_HWMON=`ls -la /sys/class/hwmon | grep $AMDGPU_PCI_ADDR | awk '{print $9}'`
HWMON_DIR=/sys/class/hwmon/${AMDGPU_HWMON}
LOGFILE=pp_printf.test.log

lspci -nn | grep "VGA\|Display"  > $LOGFILE
FILES="pp_dpm_sclk
pp_features
pp_power_profile_mode "

for f in $FILES
do
  echo === $f === >> $LOGFILE
  cat $HWMON_DIR/device/$f >> $LOGFILE
done
cat $LOGFILE

Signed-off-by: Darren Powell <darren.powell@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>