coresight: replicator: Fix panic for clearing claim tag

coresight: replicator: Fix panic for clearing claim tag

On platforms with a static replicator, a kernel panic occurs during boot:

  [    4.999406]  replicator_probe+0x1f8/0x360
  [    5.003455]  replicator_platform_probe+0x64/0xd8
  [    5.008115]  platform_probe+0x70/0xf0
  [    5.011812]  really_probe+0xc4/0x2a8
  [    5.015417]  __driver_probe_device+0x80/0x140
  [    5.019813]  driver_probe_device+0xe4/0x170
  [    5.024032]  __driver_attach+0x9c/0x1b0
  [    5.027900]  bus_for_each_dev+0x7c/0xe8
  [    5.031769]  driver_attach+0x2c/0x40
  [    5.035373]  bus_add_driver+0xec/0x218
  [    5.039154]  driver_register+0x68/0x138
  [    5.043023]  __platform_driver_register+0x2c/0x40
  [    5.047771]  coresight_init_driver+0x4c/0xe0
  [    5.052079]  replicator_init+0x30/0x48
  [    5.055865]  do_one_initcall+0x4c/0x280
  [    5.059736]  kernel_init_freeable+0x1ec/0x3c8
  [    5.064134]  kernel_init+0x28/0x1f0
  [    5.067655]  ret_from_fork+0x10/0x20

A static replicator doesn't have registers, so accessing the claim
register results in a NULL pointer deference.  Fixes the issue by
accessing the claim registers only after the I/O resource has been
successfully mapped.

Fixes: 7cd6368657f1 ("coresight: Clear self hosted claim tag on probe")
Signed-off-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250502111108.2726217-1-leo.yan@arm.com