KVM: PPC: Book3S: Remove redundant initialization of variable ret

The variable ret is being initialized with '-ENOMEM' that is meaningless.
So remove it.

Signed-off-by: Jing Xiangfeng <jingxiangfeng@huawei.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>