Kconfig: Use a short, consistent style for prompts

Consistently use

    config FOO
            bool/int/hex/string "Prompt text"

instead of

    config FOO
            bool/int/hex/string
            prompt "Prompt text"

(...and a bunch of other variations that e.g. swapped the order of the
type and the 'prompt', or put other properties between them).

The shorthand is fully equivalent to using 'prompt'. It saves lines and
avoids tricking people into thinking there is some semantic difference.

Most of the grunt work was done by a modified version of
https://unix.stackexchange.com/questions/26284/
how-can-i-use-sed-to-replace-a-multi-line-string/26290#26290, but some
of the rarer variations had to be converted manually.

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

Kconfig

@@ -5,14 +5,12 @@
 #
 
 config LIBMETAL
-	bool
-	prompt "libmetal Support"
+	bool "libmetal Support"
 	help
 	  This option enables the libmetal HAL abstraction layer
 
 config LIBMETAL_SRC_PATH
-	string
-	prompt "libmetal library source path"
+	string "libmetal library source path"
 	default "libmetal"
 	help
 	  This option specifies the path to the source for the libmetal library