iio: irsd200: fix -Warray-bounds bug in irsd200_trigger_handler

When compiling with gcc 13 with -Warray-bounds enabled:

In file included from drivers/iio/proximity/irsd200.c:15:
In function ‘iio_push_to_buffers_with_timestamp’,
    inlined from ‘irsd200_trigger_handler’ at drivers/iio/proximity/irsd200.c:770:2:
./include/linux/iio/buffer.h:42:46: error: array subscript ‘int64_t {aka long long int}[0]’
is partly outside array bounds of ‘s16[1]’ {aka ‘short int[1]’} [-Werror=array-bounds=]
   42 |                 ((int64_t *)data)[ts_offset] = timestamp;
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
drivers/iio/proximity/irsd200.c: In function ‘irsd200_trigger_handler’:
drivers/iio/proximity/irsd200.c:763:13: note: object ‘buf’ of size 2
  763 |         s16 buf = 0;
      |             ^~~

The problem seems to be that irsd200_trigger_handler() is taking a s16
variable as an int64_t buffer. As Jonathan suggested [1], fix it by
extending the buffer to a two-element array of s64.

Link: https://github.com/KSPP/linux/issues/331
Link: https://lore.kernel.org/lkml/20230809181329.46c00a5d@jic23-huawei/ [1]
Fixes: 3db3562b

 ("iio: Add driver for Murata IRS-D200")
Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
Acked-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Waqar Hameed <waqar.hameed@axis.com>
Tested-by: Waqar Hameed <waqar.hameed@axis.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230810035910.1334706-1-gongruiqi@huaweicloud.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>