kconfig: Global whitespace/consistency cleanup

Clean up space errors and use a consistent style throughout the Kconfig
files. This makes reading the Kconfig files more distraction-free, helps
with grepping, and encourages the same style getting copied around
everywhere (meaning another pass hopefully won't be needed).

Go for the most common style:

 - Indent properties with a single tab, including for choices.

   Properties on choices work exactly the same syntactically as
   properties on symbols, so not sure how the no-indentation thing
   happened.

 - Indent help texts with a tab followed by two spaces

 - Put a space between 'config' and the symbol name, not a tab. This
   also helps when grepping for definitions.

 - Do '# A comment' instead of '#A comment'

I tweaked Kconfiglib a bit to find most of the stuff.

Some help texts were reflowed to 79 columns with 'gq' in Vim as well,
though not all, because I was afraid I'd accidentally mess up
formatting.

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

subsys/shell/Kconfig

@@ -112,7 +112,7 @@ config SHELL_HISTORY_BUFFER
 	help
 	  Number of bytes dedicated for storing executed commands.
 
-endif #SHELL_HISTORY
+endif # SHELL_HISTORY
 
 config SHELL_STATS
 	bool "Enable shell statistics"

subsys/shell/Kconfig.backends

@@ -113,7 +113,7 @@ config SHELL_BACKEND_SERIAL_LOG_LEVEL
 	default 4 if SHELL_BACKEND_SERIAL_LOG_LEVEL_DBG
 	default 5 if SHELL_BACKEND_SERIAL_LOG_LEVEL_DEFAULT
 
-endif #SHELL_BACKEND_SERIAL
+endif # SHELL_BACKEND_SERIAL
 
 config SHELL_BACKEND_RTT
 	bool "Enable RTT backend"
@@ -180,7 +180,7 @@ module = SHELL_RTT
 module-str = RTT shell backend
 source "subsys/logging/Kconfig.template.log_config"
 
-endif #SHELL_BACKEND_RTT
+endif # SHELL_BACKEND_RTT
 
 config SHELL_BACKEND_TELNET
 	bool "Enable TELNET backend."