kernel-doc: fix new warning in usb.h
kernel-doc: fix new warning in usb.h

Fix new kernel-doc warning:

Warning(include/linux/usb.h:1251): No description found for parameter 'num_mapped_sgs'

Signed-off-by: Randy Dunlap <6f29df8e90a57f1ba61ffd63b0468c86bb6d3a99@xenotime.net>
Cc: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@suse.de>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas