scsi: gdth: Make option_setup() static

scsi: gdth: Make option_setup() static

Move the two functions around the '__setup' macro which uses them to avoid
an 'unused-function' warning.

This addresses the following sparse warning:

drivers/scsi/gdth.c:3229:12: warning: symbol 'option_setup' was not
declared. Should it be static?

Link: https://lore.kernel.org/r/20200918034920.3199926-1-yanaijie@huawei.com
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>