scsi: be2iscsi: Provide missing function name in header

scsi: be2iscsi: Provide missing function name in header

Fixes the following W=1 kernel build warning(s):

 drivers/scsi/be2iscsi/be_main.c:4934: warning: expecting prototype for Boot flag info for iscsi(). Prototype was for BEISCSI_SYSFS_ISCSI_BOOT_FLAGS() instead

Link: https://lore.kernel.org/r/20210312094738.2207817-21-lee.jones@linaro.org
Cc: Subbu Seetharaman <subbu.seetharaman@broadcom.com>
Cc: Ketan Mukadam <ketan.mukadam@broadcom.com>
Cc: Jitendra Bhivare <jitendra.bhivare@broadcom.com>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-drivers@broadcom.com
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>