usb: musb: avoid out of bound access in udc_setup_ep

For id = 15 an out of bound access occurs in udc_setup_ep().
Increase the size of epinfo[] from 30 to 32 to encompass
ids 0..15.

The problem was highlighted by cppcheck.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>