perf session: Move init/release code to separate functions

Separate init/release code into reader__init() and reader__release_decomp()
functions.

Remove a duplicate call to ui_progress__init_size(), the same call can
be found in __perf_session__process_events().

For multiple traces ui_progress should be initialized by total size
before reader__init() calls.

Suggested-by: Jiri Olsa <jolsa@kernel.org>
Reviewed-by: Jiri Olsa <jolsa@redhat.com>
Reviewed-by: Riccardo Mancini <rickyman7@gmail.com>
Signed-off-by: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Tested-by: Riccardo Mancini <rickyman7@gmail.com>
Acked-by: Namhyung Kim <namhyung@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Antonov <alexander.antonov@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/8bacf247de220be8e57af1d2b796322175f5e257.1634113027.git.alexey.v.bayduraev@linux.intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>