powerpc/pseries: Delete an unnecessary kfree() call in dlpar_store()

A null pointer would be passed to a call of the function “kfree”
immediately after a call of the function “kstrdup” failed at one place.
Remove this superfluous function call.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b46cc4ff-a14c-0c10-0c0c-95573a960178@web.de