usb: phy: snps: Enable auto resume feature only in host mode

If the auto resume feature is enabled in device mode,
the device is unable to detect the resume signalling
by the host in some cases.
And the auto resume feature is applicable only in
host mode. So, enable the auto resume feature only
in host mode.

Change-Id: I870ee8fdc3fe4712d072952025a37b6e954fdab8
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>