iio: light: si1133: Drop remaining uses of %hhx format string.

Since:
commit cbacb5ab ("docs: printk-formats: Stop encouraging use of
unnecessary %h[xudi] and %hh[xudi]")
use of these format strings has been discouraged.

Use the 0x02x form as the length specifier when used with # includes
the 0x prefix and is very unlikely to be what was intended by the author.

As there are not that many in IIO, this is part of an effort to clear
them out so we don't have any instances that might get copied into
new drivers.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Maxime Roussin-Bélanger <maxime.roussinbelanger@gmail.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20210603180612.3635250-3-jic23@kernel.org