Input: sa1111ps2 - extend test delay

A 2us delay is too small for the bus to settle after writing to the
register.  Extend to 10us which gives more reliable results.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>