USB: gadget: Fix Bug in to disable interrupts usecase

USB driver is using a timer to enable interrupt, so the interrupts are not
disabled for long time. If following scenario happens timer keeps getting
rearmed indefinitely. If interrupts are already enabled and call to enable
interrupts again is received, in this case we should not rearm the timer.
Timer is required to be rearmed only when interrupts are disabled and
another call for disabling interrupt is received.

This change fixes the above issue and adds some debug messages

Change-Id: I9f391d259bd441d3516323366412b5a2822382b4
Signed-off-by: Tarun Gupta <tarung@codeaurora.org>