phy: qcom: qmp: Use power_on/off ops for PCIe

The PCIe PHY initialization requires the attached device to be present,
which is primarily achieved by the PCI controller driver.  So move the
logic from init/exit to power_on/power_off.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>