usb-storage: Optimize scan delay more precisely

usb-storage: Optimize scan delay more precisely

Current storage scan delay is reduced by the following old commit.

a4a47bc03fe5 ("Lower USB storage settling delay to something more reasonable")

It means that delay is at least 'one second', or zero with delay_use=0.
'one second' is still long delay especially for embedded system but
when delay_use is set to 0 (no delay), still error observed on some USB drives.

So delay_use should not be set to 0 but 'one second' is quite long.
Especially for embedded system, it's important for end user
how quickly access to USB drive when it's connected.
That's why we have a chance to minimize such a constant long delay.

This patch optimizes scan delay more precisely
to minimize delay time but not to have any problems on USB drives
by extending module parameter 'delay_use' in milliseconds internally.
The parameter 'delay_use' optionally supports in milliseconds
if it ends with 'ms'.
It makes the range of value to 1 / 1000 in internal 32-bit value
but it's still enough to set the delay time.
By default, delay time is 'one second' for backward compatibility.

For example, it seems to be good by changing delay_use=100ms,
that is 100 millisecond delay without issues for most USB pen drives.

Signed-off-by: Norihiko Hama <Norihiko.Hama@alpsalpine.com>
Link: https://lore.kernel.org/r/20240515004339.29892-1-Norihiko.Hama@alpsalpine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>