zdump: Drop support of obsolete dumps and dumpers

Drop support of obsolete dump and dump-tool versions (single-volume DASD,
FBA and Tape) in order to simplify zgetdump logic:
- CCW dumpers written in assembler instructions as well as stage2 dumpers
  of size less than 0x3000 (STAGE2_DUMPER_SIZE_V1 or STAGE2_DUMPER_SIZE_V2)
  haven't been used for years. Remove its traces completely as a cleanup.
  Keep the last version (version 5) of non-extended DASD dumper as well as
  newer extended DASD dumpers.
- Rename STAGE2_DUMPER_SIZE_V3 and STAGE2_DUMPER_SIZE_ZLIB constants.
- Drop support of non-extended s390 dumps of version < 5. Dump files
  of s390 format version 5 can be still produced by zgetdump (dfo_s390).
- Drop excessive dump version checking in df_s390_cpu_info_add() and
  df_s390_hdr_add() considering that obsolete s390 dumps of version lower
  than 5 no longer supported.
- Use cpu_cnt field in s390 dump header instead of the s390 dump version to
  indicate no cpu info available (DFI_CPU_CONTENT_NONE) for dfo_s390.
- Make df_s390_dumper_read() return error code upon unknown dumper
  version/magic detection.

Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zipl/boot/eckd2dump.lds.S

@@ -49,7 +49,7 @@ SECTIONS
     ASSERT(__stage2dump_tail_end - __stage2_head == STAGE2_DUMPER_SIZE_MV,
            "MV dumper size doesn't conform to the described memory layout");
 #else
-    ASSERT(__stage2dump_tail_end - __stage2_head == STAGE2_DUMPER_SIZE_ZLIB,
+    ASSERT(__stage2dump_tail_end - __stage2_head == STAGE2_DUMPER_SIZE_SV_ZLIB,
            "SV dumper size doesn't conform to the described memory layout");
 #endif
   }