usb: gadget: qdss: Fix runtime PM usage count for multiple set_alt

In some scenarios such as USBCV tests, multiple set_alt
could be issued with same interface setting. In that case,
driver get the usage count in set_alt but do not put it.
This causes a mismatch of usage count and DWC3 LPM does
not work anymore. Fix this by adding check in qdss_set_alt to
ignore multiple set_alts.

Change-Id: I232456c3f99b0cfaa61eb1c044bdd86013c930fa
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>