i2c: nomadik: remove an unnecessary NULL check in nmk_i2c_remove()

"res" can't be NULL because it's a pointer to somewhere in the middle of
the "adev" struct.  Also probe() succeeded so there is no need to check
here.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>