ide/Kconfig: use 'on-board' instead of 'built-in' in config options

To avoid confusion between 'built-in' drivers and 'on-board'
controllers, consistently use the term 'on-board' for controllers.

Minor line-wrapping improvements in descriptions for config options.

[ Bart: thanks to Jan for 'built-in'->'on-board' suggestion ]

Signed-off-by: Frans Pop <elendil@planet.nl>
Cc: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>