w1: mxc_w1: Fix timeout resolution problem leading to bus error

w1: mxc_w1: Fix timeout resolution problem leading to bus error

On my platform (i.MX53) bus access sometimes fails with
	w1_search: max_slave_count 64 reached, will continue next search.

The reason is the use of jiffies to implement a 200us timeout in
mxc_w1_ds2_touch_bit().
On some platforms the jiffies timer resolution is insufficient for this.

Fix by replacing jiffies by ktime_get().

For consistency apply the same change to the other use of jiffies in
mxc_w1_ds2_reset_bus().

Fixes: f80b2581a706 ("w1: mxc_w1: Optimize mxc_w1_ds2_touch_bit()")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
Link: https://lore.kernel.org/r/1601455030-6607-1-git-send-email-martin.fuzzey@flowbird.group
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>