powerpc/pseries: Don't print failure message in energy driver

This driver currently reports the H_BEST_ENERGY hypervisor call is
unsupported (even when booting in a non-virtualised environment). This
is not something the administrator can do much with, and not
significant for debugging.

Remove it.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>