phy: qcom: Rework Kconfig logic around MSM8916_USB_PHY

phy: qcom: Rework Kconfig logic around MSM8916_USB_PHY

This PHY driver is required by USB_EHCI_MSM and not useful on its own.
Rather than have it be a prompted option, it should (and currently is)
select'd by USB_EHCI_MSM. Remove the prompt for this option and then
correct the dependency chain (it must select PHY).

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Casey Connolly <casey.connolly@linaro.org>
Link: https://lore.kernel.org/r/20251003203927.1030052-1-trini@konsulko.com
Signed-off-by: Casey Connolly <kcxt@postmarketos.org>