i2c: highlander: Use proper printk format for size_t

size_t should be printed with its own format to be 64-bit friendly and
fix warning when compiling on 64-bit platform (e.g. with COMPILE_TEST):

    drivers/i2c/busses/i2c-highlander.c: In function ‘highlander_i2c_smbus_xfer’:
    drivers/i2c/busses/i2c-highlander.c:325:22: warning:
        format ‘%d’ expects argument of type ‘int’,
        but argument 3 has type ‘size_t {aka long unsigned int}’ [-Wformat=]

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>