SYSFS: Fix return values for sysdev_store_{ulong,int}

Always return the full size instead of the consumed
length of the string in sysdev_store_{ulong,int}

This avoids EINVAL errors in some echo versions.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>