pmdomain: arm: scmi: Fix genpd leak on provider registration failure

pmdomain: arm: scmi: Fix genpd leak on provider registration failure

If of_genpd_add_provider_onecell() fails during probe, the previously
created generic power domains are not removed, leading to a memory leak
and potential kernel crash later in genpd_debug_add().

Add proper error handling to unwind the initialized domains before
returning from probe to ensure all resources are correctly released on
failure.

Example crash trace observed without this fix:

  | Unable to handle kernel paging request at virtual address fffffffffffffc70
  | CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.18.0-rc1 #405 PREEMPT
  | Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform
  | pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  | pc : genpd_debug_add+0x2c/0x160
  | lr : genpd_debug_init+0x74/0x98
  | Call trace:
  |  genpd_debug_add+0x2c/0x160 (P)
  |  genpd_debug_init+0x74/0x98
  |  do_one_initcall+0xd0/0x2d8
  |  do_initcall_level+0xa0/0x140
  |  do_initcalls+0x60/0xa8
  |  do_basic_setup+0x28/0x40
  |  kernel_init_freeable+0xe8/0x170
  |  kernel_init+0x2c/0x140
  |  ret_from_fork+0x10/0x20

Fixes: 898216c97ed2 ("firmware: arm_scmi: add device power domain support using genpd")
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>