Fix a compiler warning in src/lib/usbdebug.c (trivial).

The 'delay' variable shadows the global 'delay()' function, yielding
this compiler warning/error:

src/pc80/../lib/usbdebug.c: In function `ehci_reset_port':
src/pc80/../lib/usbdebug.c:281: error: declaration of `delay' shadows a global declaration
src/lib/delay.c:9: error: shadowed declaration is here

This fixes the issue by renaming the 'delay' variable to 'delay_ms'.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5826 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1