samples: fix binderfs sample

A routine check for misspelled Kconfig symbols showed on instance
from last year, the correct symbol name is CONFIG_ANDROID_BINDERFS,
not CONFIG_CONFIG_ANDROID_BINDERFS, so the extra prefix must
be removed in the Kconfig file to allow enabling the sample.

As the actual sample fails to build as a kernel module, change the
Makefile enough to get to build as a hostprog instead.

Fixes: 9762dc14 ("samples: add binderfs sample program")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20200428212555.2806258-1-arnd@arndb.deSigned-off-by: Jonathan Corbet <corbet@lwn.net>

samples/Kconfig

@@ -171,7 +171,7 @@ config SAMPLE_VFIO_MDEV_MBOCHS
 
 config SAMPLE_ANDROID_BINDERFS
 	bool "Build Android binderfs example"
-	depends on CONFIG_ANDROID_BINDERFS
+	depends on ANDROID_BINDERFS
 	help
 	  Builds a sample program to illustrate the use of the Android binderfs
 	  filesystem.

samples/binderfs/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
-obj-$(CONFIG_SAMPLE_ANDROID_BINDERFS) += binderfs_example.o
+ifndef CROSS_COMPILE
+ifdef CONFIG_SAMPLE_ANDROID_BINDERFS
+hostprogs := binderfs_example
+endif
+endif