OvmfPkg/LsiScsiDxe: Report Targets and LUNs

Implement LsiScsiGetNextTargetLun(), LsiScsiBuildDevicePath(),
LsiScsiGetTargetLun(), and LsiScsiGetNextTarget() to report Targets and
LUNs and build the device path.

This commit also introduces two PCD value: PcdLsiScsiMaxTargetLimit and
PcdLsiScsiMaxLunLimit as the limits for Targets and LUNs.

v3:
  - Update the range of LUN in the assertioin
  - Squash the spurious newline into the previous commit
v2:
  - Zero out (*Target) in LsiScsiGetTargetLun()
  - Use CopyMem() instead of the one-byte shortcut to copy target from
    ScsiDevicePath->Pun
  - Add asserts for PcdLsiScsiMaxTargetLimit and PcdLsiScsiMaxLunLimit

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Gary Lin <glin@suse.com>
Message-Id: <20200717061130.8881-7-glin@suse.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

OvmfPkg/LsiScsiDxe/LsiScsi.h

@@ -14,6 +14,8 @@
 
 typedef struct {
   UINT32                          Signature;
+  UINT8                           MaxTarget;
+  UINT8                           MaxLun;
   EFI_EXT_SCSI_PASS_THRU_MODE     PassThruMode;
   EFI_EXT_SCSI_PASS_THRU_PROTOCOL PassThru;
 } LSI_SCSI_DEV;