KVM: PPC: Book3S HV: Fix the get_one_reg of SDAR

The kvmppc_get_one_reg_hv() for SDAR is wrongly getting the SIAR
instead of SDAR, possibly a paste error emanating from the previous
refactoring.

Patch fixes the wrong get_one_reg() for the same.

Fixes: ebc88ea7 ("KVM: PPC: Book3S HV: Use accessors for VCPU registers")
Signed-off-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/171759278410.1480.16404209606556979576.stgit@linux.ibm.com