set iostat_period_ms to 1 sec

Current period of this is 3 sec and it is used when Perfetto profiling is running on Android. Without Perfetto profiling, it doesn't affect the system at all. However, 3 sec doesn't provide enough granularity to understand F2FS I/O behaviors. To make F2FS I/O profiling ftrace effective, set the ftrace period to 1 sec.

Test: check f2fs iostat_period_ms sysfs node value
Change-Id: I2d418795613dfbd1aea6c4f13c9a39af3deb1c4d
Signed-off-by: Daeho Jeong <daehojeong@google.com>