tmp105: Fix I2C protocol bug

An early length postincrement in the TMP105's I2C TX path led to
transfers of more than one byte to place the second byte in the third
byte's place within the buffer and the third byte to get discarded.

Fix this by explictly incrementing the length after the checks but
before the callback is called, which again checks the length.

Adjust the Coding Style while at it.

Signed-off-by: Alex Horn <alex.horn@cs.ox.ac.uk>
Signed-off-by: Andreas Färber <andreas.faerber@web.de>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
