3 bytes were being read but 4 were being written. Explicitly initialize
the unused bytes to 0 and refactor the loop to use direct array
indexing, which appears to silence a Clang false positive warning[1].

Indent improvement included for readability of the fixed code.

Link: https://github.com/ClangBuiltLinux/linux/issues/2000 [1]
Fixes: ac78c6aa ("iio: pressure: Add driver for DLH pressure sensors")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240223172936.it.875-kees@kernel.org
Cc: <Stable@vger.kerenl.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>