USB: isp1362: remove unused _BUG_ON() calls

We shouldn't ever panic in a driver, and these calls were never being
used, so just delete them, as obviously the driver is working properly
now (right?)

Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>