kconfig: show sub-menu entries even if the prompt is hidden

Since commit f79dc03f ("kconfig: refactor choice value
calculation"), when EXPERT is disabled, nothing within the "if INPUT"
... "endif" block in drivers/input/Kconfig is displayed. This issue
affects all command-line interfaces and GUI frontends.

The prompt for INPUT is hidden when EXPERT is disabled. Previously,
menu_is_visible() returned true in this case; however, it now returns
false, resulting in all sub-menu entries being skipped.

Here is a simplified test case illustrating the issue:

    config A
           bool "A" if X
           default y

    config B
           bool "B"
           depends on A

When X is disabled, A becomes unconfigurable and is forced to y.
B should be displayed, as its dependency is met.

This commit restores the necessary code, so menu_is_visible() functions
as it did previously.

Fixes: f79dc03f ("kconfig: refactor choice value calculation")
Reported-by: Edmund Raile <edmund.raile@proton.me>
Closes: https://lore.kernel.org/all/5fd0dfc7ff171aa74352e638c276069a5f2e888d.camel@proton.me/


Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>