i2c: xiic: Do not reset controller before every transfer

Currently before every transfer the controller is reinitialised.
We are already resetting the controller upon errors so upon every
transfer is a performance kill.
Remove the same.

Signed-off-by: Shubhrajyoti Datta <shubhraj@xilinx.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>