Fix the following sparse warning:
classmate-laptop.c:523:61: warning: Using plain integer as NULL pointer
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
 {
        union acpi_object param[2];
        struct acpi_object_list input;
-       struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, 0 };
+       struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
        unsigned char *locs;
        acpi_status status;