checkpatch: kconfig: recognize more prompts when checking help texts

The check for a missing or short help text only considers symbols with a
prompt, but doesn't recognize any of the following as a prompt:

	bool 'foo'
	tristate 'foo'
	prompt "foo"
	prompt 'foo'

Make the check recognize those too.

Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>