drivers/macintosh: Fix memleak in windfarm_pm112 driver

drivers/macintosh: Fix memleak in windfarm_pm112 driver

create_cpu_loop() calls smu_sat_get_sdb_partition() which does
kmalloc() and returns the allocated buffer. In fact it's called twice,
and neither buffer is freed.

This results in a memory leak as reported by Erhard:
  unreferenced object 0xc00000047081f840 (size 32):
    comm "kwindfarm", pid 203, jiffies 4294880630 (age 5552.877s)
    hex dump (first 32 bytes):
      c8 06 02 7f ff 02 ff 01 fb bf 00 41 00 20 00 00  ...........A. ..
      00 07 89 37 00 a0 00 00 00 00 00 00 00 00 00 00  ...7............
    backtrace:
      [<0000000083f0a65c>] .smu_sat_get_sdb_partition+0xc4/0x2d0 [windfarm_smu_sat]
      [<000000003010fcb7>] .pm112_wf_notify+0x104c/0x13bc [windfarm_pm112]
      [<00000000b958b2dd>] .notifier_call_chain+0xa8/0x180
      [<0000000070490868>] .blocking_notifier_call_chain+0x64/0x90
      [<00000000131d8149>] .wf_thread_func+0x114/0x1a0
      [<000000000d54838d>] .kthread+0x13c/0x190
      [<00000000669b72bc>] .ret_from_kernel_thread+0x58/0x64
  unreferenced object 0xc0000004737089f0 (size 16):
    comm "kwindfarm", pid 203, jiffies 4294880879 (age 5552.050s)
    hex dump (first 16 bytes):
      c4 04 01 7f 22 11 e0 e6 ff 55 7b 12 ec 11 00 00  ...."....U{.....
    backtrace:
      [<0000000083f0a65c>] .smu_sat_get_sdb_partition+0xc4/0x2d0 [windfarm_smu_sat]
      [<00000000b94ef7e1>] .pm112_wf_notify+0x1294/0x13bc [windfarm_pm112]
      [<00000000b958b2dd>] .notifier_call_chain+0xa8/0x180
      [<0000000070490868>] .blocking_notifier_call_chain+0x64/0x90
      [<00000000131d8149>] .wf_thread_func+0x114/0x1a0
      [<000000000d54838d>] .kthread+0x13c/0x190
      [<00000000669b72bc>] .ret_from_kernel_thread+0x58/0x64

Fix it by rearranging the logic so we deal with each buffer
separately, which then makes it easy to free the buffer once we're
done with it.

Fixes: ac171c46667c ("[PATCH] powerpc: Thermal control for dual core G5s")
Cc: stable@vger.kernel.org # v2.6.16+
Reported-by: Erhard F. <erhard_f@mailbox.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Erhard F. <erhard_f@mailbox.org>
Link: https://lore.kernel.org/r/20200423060038.3308530-1-mpe@ellerman.id.au