docbook: don't use serial_core.h in device-drivers book
docbook: don't use serial_core.h in device-drivers book

Fix new kernel-doc warning.  This file no longer contains
kernel-doc comments.

Warning(include/linux/serial_core.h): no structured comments found

Signed-off-by: Randy Dunlap <6f29df8e90a57f1ba61ffd63b0468c86bb6d3a99@xenotime.net>
Cc: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@suse.de>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@suse.de>

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