serial: qcom_geni: Comment use of devm_krealloc rather than devm_krealloc_array

serial: qcom_geni: Comment use of devm_krealloc rather than devm_krealloc_array

Now that devm_krealloc_array is available, add a comment justifying not
changing this occurrence to avoid any future auto fixups.

Link: https://lore.kernel.org/all/20230318173402.20a4f60d@jic23-huawei/
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20230509094942.396150-5-james.clark@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>