usb: f_mass_storage: sleep_thread: decrease the interval for check ctrlc()

This change decreases the interval of calls to:
- display busy indicator
- check ctrlc()
- check cable connection

By this change, breaking the UMS command is more easy on Odroid XU3.

Signed-off-by: Inha Song <ideal.song@samsung.com>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Marek Vasut <marex@denx.de>