usb: gsi: Fix runtime PM usage count for MBIM interface

GSI Driver get the usage count in work handler when set_alt 1 happens
and this counter will decrement in disconnect work due to cable disconnect
or in gsi_suspend for suspended state.

In this case set alt to 0 came for MBIM interface and clear the
data_interface_up flag. After that suspend happens and does not decrement
the counter in gsi_suspend. This causes a mismatch of usage count and
usb not entering to low power mode.

Fix this by checking for USB_PROT_GPS_CTRL instead of data_interface_up.

Change-Id: Iaabf3de46ed72e33980d1e3e386e8ca0ae651c74
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>