Added usbtty_configured() check. Fixed attribute(packed) warnings.

Added usbtty_configured() check. Fixed attribute(packed) warnings.

V3: Fixed line-wrap problem due to user error in mail!

Added usb_configured() checks in usbtty_puts() and usbtty_putc() to get around a hang
when usb is not connected and the user has set up multi-io (setenv stdout serial,usbtty etc).
Got rid of redundant __attribute__((packed)) directives that were causing warnings from gcc.

Signed-off-by: Atin Malaviya <atin.malaviya@gmail.com>
Signed-off-by: Remy Bohmer <linux@bohmer.net>