Revert "ALSA: usb-audio: Clear fixed clock rate at closing EP"

This reverts commit 8ca3315b which is
commit 809f44a0 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Ida23c2d5a4c347a7d38d7dddcb9a9205a21f9a47
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>