x86/pmem: Fix platform-device leak in error path

[ Upstream commit 229e73d46994f15314f58b2d39bf952111d89193 ]

Make sure to free the platform device in the unlikely event that
registration fails.

Fixes: 7a67832c ("libnvdimm, e820: make CONFIG_X86_PMEM_LEGACY a tristate option")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220620140723.9810-1-johan@kernel.org


Signed-off-by: Sasha Levin <sashal@kernel.org>