scsi: mpt3sas: Make MPI26_CONFIG_PAGE_PIOUNIT_1::PhyData[] a flexible array

This terminal 1-length variable array can be directly converted into a C99
flexible array member.

As all users of MPI26_CONFIG_PAGE_PIOUNIT_1 (Mpi26PCIeIOUnitPage1_t) do not
use PhyData[], no further source changes are required to accommodate its
reduced sizeof():

 - mpt3sas_config.c:mpt3sas_config_get_pcie_iounit_pg1() fetches a
   Mpi26PCIeIOUnitPage1_t into a caller-provided buffer, and may fetch
   and write PhyData[] into that buffer depending on its sz argument.
   It has one caller:

   - mpt3sas_base.c:_base_assign_fw_reported_qd() passes
     sizeof(Mpi26PCIeIOUnitPage1_t) as sz, but does not use PhyData[].

Signed-off-by: James Seo <james@equiv.tech>
Link: https://lore.kernel.org/r/20230806170604.16143-7-james@equiv.tech
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpt3sas/mpi/mpi2_cnfg.h

@@ -3668,12 +3668,9 @@ typedef struct _MPI26_PCIE_IO_UNIT1_PHY_DATA {
 #define MPI26_PCIEIOUNIT1_LINKFLAGS_SRNS_EN                 (0x02)
 
 /*
- *Host code (drivers, BIOS, utilities, etc.) should leave this define set to
- *one and check the value returned for NumPhys at runtime.
+ *Host code (drivers, BIOS, utilities, etc.) should check the value returned
+ *for NumPhys at runtime before using PhyData[].
  */
-#ifndef MPI26_PCIE_IOUNIT1_PHY_MAX
-#define MPI26_PCIE_IOUNIT1_PHY_MAX      (1)
-#endif
 
 typedef struct _MPI26_CONFIG_PAGE_PIOUNIT_1 {
 	MPI2_CONFIG_EXTENDED_PAGE_HEADER	Header;	/*0x00 */
@@ -3685,7 +3682,7 @@ typedef struct _MPI26_CONFIG_PAGE_PIOUNIT_1 {
 	U8	DMDReportPCIe;                      /*0x11 */
 	U16	Reserved2;                          /*0x12 */
 	MPI26_PCIE_IO_UNIT1_PHY_DATA
-		PhyData[MPI26_PCIE_IOUNIT1_PHY_MAX];/*0x14 */
+		PhyData[];                          /*0x14 */
 } MPI26_CONFIG_PAGE_PIOUNIT_1,
 	*PTR_MPI26_CONFIG_PAGE_PIOUNIT_1,
 	Mpi26PCIeIOUnitPage1_t, *pMpi26PCIeIOUnitPage1_t;