viafb: reduce I2C timeout and delay

This patch reduces the value for I2C timeout and udelay.
The udelay was reduced to 10 (old: 40) which is still very high as for
standard-mode I2C even 5 should work. This gives a speedup of factor 4
when talking to I2C devices.
The timeout was reduced to 2 (old: 20) which is taken from the radeon
driver so it should work as well. This gives a speedup of factor 10 when
detecting that there is no I2C device we want to talk to.
This causes a huge improvement of device initialization time.

Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Cc: Joseph Chan <JosephChan@via.com.tw>