usb: dwc3: Remove kernel doc annotation where it's not needed

The main comment in the file mistakenly marked with kernel doc annotation
which makes the parser unhappy:

.../dwc3/host.c:16: warning: Function parameter or member 'dwc' not described in 'dwc3_host_get_irq'

Drop kernel doc annotation from host.c module.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>