KVM: PPC: Book3S HV: Fix function definition in book3s_hv_uvmem.c

Without this fix, git is confused. It generates wrong
function context for code changes in subsequent patches.
Weird, but true.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>