target/ppc: init 'rmmu_info' in kvm_get_radix_page_info()

target/ppc: init 'rmmu_info' in kvm_get_radix_page_info()

Init the struct to avoid Valgrind complaints about unitialized bytes,
such as this one:

==39549== Syscall param ioctl(generic) points to uninitialised byte(s)
==39549==    at 0x55864E4: ioctl (in /usr/lib64/libc.so.6)
==39549==    by 0xD1F7EF: kvm_vm_ioctl (kvm-all.c:3035)
==39549==    by 0xAF8F5B: kvm_get_radix_page_info (kvm.c:276)
==39549==    by 0xB00533: kvmppc_host_cpu_class_init (kvm.c:2369)
==39549==    by 0xD3DCE7: type_initialize (object.c:366)
==39549==    by 0xD3FACF: object_class_foreach_tramp (object.c:1071)
==39549==    by 0x502757B: g_hash_table_foreach (in /usr/lib64/libglib-2.0.so.0.7000.5)
==39549==    by 0xD3FC1B: object_class_foreach (object.c:1093)
==39549==    by 0xB0141F: kvm_ppc_register_host_cpu_type (kvm.c:2613)
==39549==    by 0xAF87E7: kvm_arch_init (kvm.c:157)
==39549==    by 0xD1E2A7: kvm_init (kvm-all.c:2595)
==39549==    by 0x8E6E93: accel_init_machine (accel-softmmu.c:39)
==39549==  Address 0x1fff00e208 is on thread 1's stack
==39549==  in frame #2, created by kvm_get_radix_page_info (kvm.c:267)
==39549==  Uninitialised value was created by a stack allocation
==39549==    at 0xAF8EE8: kvm_get_radix_page_info (kvm.c:267)

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220331001717.616938-5-danielhb413@gmail.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>