cxl/pmu: Ensure put_device on pmu devices

The following kmemleaks were detected when removing the cxl module
stack:

unreferenced object 0xffff88822616b800 (size 1024):
...
  backtrace:
    [<00000000bedc6f83>] kmalloc_trace+0x26/0x90
    [<00000000448d1afc>] devm_cxl_pmu_add+0x3a/0x110 [cxl_core]
    [<00000000ca3bfe16>] 0xffffffffa105213b
    [<00000000ba7f78dc>] local_pci_probe+0x41/0x90
    [<000000005bb027ac>] pci_device_probe+0xb0/0x1c0
...
unreferenced object 0xffff8882260abcc0 (size 16):
...
  hex dump (first 16 bytes):
    70 6d 75 5f 6d 65 6d 30 2e 30 00 26 82 88 ff ff  pmu_mem0.0.&....
  backtrace:
...
    [<00000000152b5e98>] dev_set_name+0x43/0x50
    [<00000000c228798b>] devm_cxl_pmu_add+0x102/0x110 [cxl_core]
    [<00000000ca3bfe16>] 0xffffffffa105213b
    [<00000000ba7f78dc>] local_pci_probe+0x41/0x90
    [<000000005bb027ac>] pci_device_probe+0xb0/0x1c0
...
unreferenced object 0xffff8882272af200 (size 256):
...
  backtrace:
    [<00000000bedc6f83>] kmalloc_trace+0x26/0x90
    [<00000000a14...