i2c: bcm2835: Avoid clock stretching timeouts

The CLKT register contains at poweron 0x40, which at our typical 100kHz
bus rate means .64ms. But there is no specified limit to how long devices
should be able to stretch the clocks, so just disable the timeout. We
still have a timeout wrapping the entire transfer.

Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
BugLink: https://github.com/raspberrypi/linux/issues/3064


Signed-off-by: Wolfram Sang <wsa@kernel.org>