kconfig: Remove symbol types from Kconfig.defconfig files

Same deal as in commit 7fdb5257 ("kconfig: Use 'default' instead of
'def_bool' in Kconfig.defconfig files"), but I hacked Kconfiglib to also
find cases where the type is given separately as e.g.

    config FOO
            int
            default 3

Motivation (from a note in
https://docs.zephyrproject.org/latest/guides/kconfig/index.html

):

    For a symbol defined in multiple locations (e.g., in a
    Kconfig.defconfig file in Zephyr), it is best to only give the
    symbol type for the "base" definition of the symbol, and to use
    'default' (instead of 'def_<type>' value) for the remaining
    definitions. That way, if the base definition of the symbol is
    removed, the symbol ends up without a type, which generates a
    warning that points to the other definitions. That makes the extra
    definitions easier to discover and remove.

It's also nice if 'def_bool' and the like turn into a semi-reliable flag
that the symbol is only defined in Kconfig.defconfig files. That might
be a sign that things could be cleaned up.

Will do a separate pass later to remove some symbols only defined in
Kconfig.defconfig files.

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>