perf tools: Fix module symbol processing

The 'dso->kernel' condition is true also for kernel modules now,
and there are several places that were omited by the initial change:

  - we need to identify modules separately in dso__process_kernel_symbol
  - we need to set 'dso->kernel' for module from buildid table
  - there's no need to use 'dso->kernel || kmodule' in one condition

Committer testing:

Before:

  # perf test -v object
  <SNIP>
  Objdump command is: objdump -z -d --start-address=0xffffffff813e682f --stop-address=0xffffffff813e68af /usr/lib/debug/lib/modules/5.7.14-200.fc32.x86_64/vmlinux
  Bytes read match those read by objdump
  Reading object code for memory address: 0xffffffffc02dc257
  File is: /lib/modules/5.7.14-200.fc32.x86_64/kernel/arch/x86/crypto/crc32c-intel.ko.xz
  On file address is: 0xffffffffc02dc2e7
  dso__data_read_offset failed
  test child finished with -1
  ---- end ----
  Object code reading: FAILED!
  #

After:

  # perf test object
  26: Object code reading                                   : Ok
  # perf test object
  26: Object code reading                                   : Ok
  # perf test object
  26: Object code reading                                   : Ok
  # perf test object
  26: Object code reading                                   : Ok
  # perf test object
  26: Object code reading                                   : Ok
  #

Fixes: 02213cec

 ("perf maps: Mark module DSOs with kernel type")
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>