i2c: tegra: fix maximum transfer size

commit f4e3f4ae1d9c9330de355f432b69952e8cef650c upstream.

Tegra186 and prior supports maximum 4K bytes per packet transfer
including 12 bytes of packet header.

This patch fixes max write length limit to account packet header
size for transfers.

Cc: stable@vger.kernel.org # 4.4+

Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>