kconfig: Remove some redundant single-item menus and ifs

A single menu within an if like

    if FOO

    menu "blah"

    ...

    endmenu

    endif

can be replaced with

    menu "blah"
            depends on FOO

    ...

    endmenu

Fix up all existing instances.

Also remove redundant extra menus underneath 'menuconfig' symbols.
'menuconfig' already creates a menu.

Also remove the menu in arch/arm/core/aarch32/Kconfig around the
"Floating point ABI" choice. The choice depends on FLOAT, which depends
on CPU_HAS_CPU, so remove the 'depends on CPU_HAS_FPU' too.

Piggyback removing a redundant 'default n' for BME280.

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