KVM: s390: fix guest fprs memory leak

KVM: s390: fix guest fprs memory leak

commit 9c7ebb613bffea2feef4ec562ba1dbcaa810942b upstream.

fprs is never freed, therefore resulting in a memory leak if
kvm_vcpu_init() fails or the vcpu is destroyed.

Fixes: 9977e886cbbc ("s390/kernel: lazy restore fpu registers")
Reported-by: Eric Farman <farman@linux.vnet.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: Eric Farman <farman@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>