powerpc/pseries: Fix CONFIG_DTL=n build

The recently moved dtl code must be compiled-in if
CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y even if CONFIG_DTL=n.

Fixes: 6ba5aa54 ("powerpc/pseries: Move dtl scanning and steal time accounting to pseries platform")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221013073131.1485742-1-npiggin@gmail.com