scsi: megaraid_sas: Make some symbols static

Fix sparse warnings:

drivers/scsi/megaraid/megaraid_sas_base.c:271:1: warning: symbol 'megasas_issue_dcmd' was not declared. Should it be static?
drivers/scsi/megaraid/megaraid_sas_base.c:2227:6: warning: symbol 'megasas_do_ocr' was not declared. Should it be static?
drivers/scsi/megaraid/megaraid_sas_base.c:3194:25: warning: symbol 'megaraid_host_attrs' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>