Bool symbols implicitly default to 'n'.
A 'default n' can make sense e.g. in a Kconfig.defconfig file, if you
want to override a 'default y' on the base definition of the symbol. It
isn't used like that on any of these symbols though, and is
inconsistent.
This will make the auto-generated Kconfig documentation have "No
defaults. Implicitly defaults to n." as well, which is clearer than
'default n if ...'
Piggyback a missing 'source "drivers/gpio/Kconfig.imx"'. This file
wasn't included anywhere previously.
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
