thermal: power_allocator: Fix Kconfig warning

When do randbuiding, we got this:

WARNING: unmet direct dependencies detected for THERMAL_GOV_POWER_ALLOCATOR
  Depends on [n]: THERMAL [=y] && ENERGY_MODEL [=n]
  Selected by [y]:
  - THERMAL_DEFAULT_GOV_POWER_ALLOCATOR [=y] && <choice>

The Kconfig option THERMAL_DEFAULT_GOV_POWER_ALLOCATOR selects the
THERMAL_GOV_POWER_ALLOCATOR but this one depends on the ENERGY_MODEL
which is not enabled.

Make THERMAL_DEFAULT_GOV_POWER_ALLOCATOR depend on THERMAL_GOV_POWER_ALLOCATOR
to fix this warning.

Suggested-by: Quentin Perret <qperret@google.com>
Fixes: a4e893e8 ("thermal: cpu_cooling: Migrate to using the EM framework")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20191113105313.41616-1-yuehaibing@huawei.com