reg_dumper: change and fix behavior when using dump files

Before this patch, handling dump files was wrong:
- when HAS_PCH_SPLIT was specified, intel_reg_dumper segfaulted inside
  intel_check_pch()
- the "devid" variable was used but not set
- there was no way to specify the device id of the machine used to
  generate the dump file

This patch fixes this behavior with the following changes:
- the HAS_PCH_SPLIT variable is gone
- there is now a '-d' argument that can be used to specify the device id
  used to interpret the results
- when a dump file is used but the '-d' argument is not provided, an
  Ironlake machine is assumed

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

man/intel_reg_dumper.man

@@ -4,7 +4,7 @@
 .SH NAME
 intel_reg_dumper \- Decode a bunch of Intel GPU registers for debugging
 .SH SYNOPSIS
-.B intel_reg_dumper [ file ]
+.B intel_reg_dumper [ options ] [ file ]
 .SH DESCRIPTION
 .B intel_reg_dumper
 is a tool to read and decode the values of many Intel GPU registers.  It is
@@ -14,11 +14,20 @@ argument is present, the registers will be decoded from the given file
 instead of the current registers.  Use the
 .B intel_reg_snapshot
 tool to generate such files.
-.SH ENVIRONMENT
-.BR HAS_PCH_SPLIT
-.PP
-If set, decode as though the GPU has a PCH split.  This is only necessary for
-Intel HD (Ironlake) and later register dumps in files; live decodes get this
-correct automatically.
+
+When the
+.B file
+argument is present and the
+.B -d
+argument is not present,
+.B intel_reg_dumper
+will assume the file was generated on an Ironlake machine.
+.SH OPTIONS
+.TP
+.B -d id
+when a dump file is used, use 'id' as device id (in hex)
+.TP
+.B -h
+prints a help message
 .SH SEE ALSO
 .BR intel_reg_snapshot(1)