kconfig: Clean up header comments and make them consistent

Use this short header style in all Kconfig files:

    # <description>

    # <copyright>
    # <license>

    ...

Also change all <description>s from

    # Kconfig[.extension] - Foo-related options

to just

    # Foo-related options

It's clear enough that it's about Kconfig.

The <description> cleanup was done with this command, along with some
manual cleanup (big letter at the start, etc.)

    git ls-files '*Kconfig*' | \
        xargs sed -i -E '1 s/#\s*Kconfig[\w.-]*\s*-\s*/# /'

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

soc/xtensa/esp32/Kconfig.defconfig

@@ -1,5 +1,5 @@
-# Kconfig - ESP32 board configuration
-#
+# ESP32 board configuration
+
 # Copyright (c) 2017 Intel Corporation
 # SPDX-License-Identifier: Apache-2.0
 

soc/xtensa/intel_s1000/Kconfig.defconfig

@@ -1,5 +1,5 @@
-# Kconfig - XTENSA board configuration
-#
+# XTENSA board configuration
+
 # Copyright (c) 2017 Intel Corporation
 # SPDX-License-Identifier: Apache-2.0
 

soc/xtensa/sample_controller/Kconfig.defconfig

@@ -1,5 +1,5 @@
-# Kconfig - XTENSA board configuration
-#
+# XTENSA board configuration
+
 # Copyright (c) 2016 Open-RnD Sp. z o.o.
 # Copyright (c) 2016 Cadence Design Systems, Inc.
 # SPDX-License-Identifier: Apache-2.0