net: stmmac: Disable c-tile power collapse

Disable c-tile PC from stmmac driver.
This stops stmmac power collapse in XO-shutdown.

Change-Id: Iae7c6d2a2edf29475b5befae91a7b19a6ab2b2ce
Acked-by: Abhishek Chauhan <abchauha@qti.qualcomm.com>
Signed-off-by: Sunil Paidimarri <hisunil@codeaurora.org>