cnss2: Add cnss usb API to check the target status

Add new cnss usb API to check to check whether the target
is up or down. Remove invoking pld_remove callback function
in usb disconnect.

Change-Id: I0e873737a27f9941db1dae54636ef55ba4d05288
Signed-off-by: Jayachandran Sreekumaran <jsreekum@codeaurora.org>