mtd: tests: annotate as DANGEROUS in Kconfig

The tests may erase mtd devices, so annotate them as suggested per
coding style and add a paragraph to the help text as well.

Artem: amended the help test a bit.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@intel.com>

drivers/mtd/Kconfig

@@ -13,13 +13,16 @@ menuconfig MTD
 if MTD
 
 config MTD_TESTS
-	tristate "MTD tests support"
+	tristate "MTD tests support (DANGEROUS)"
 	depends on m
 	help
 	  This option includes various MTD tests into compilation. The tests
 	  should normally be compiled as kernel modules. The modules perform
 	  various checks and verifications when loaded.
 
+	  WARNING: some of the tests will ERASE entire MTD device which they
+	  test. Do not use these tests unless you really know what you do.
+
 config MTD_REDBOOT_PARTS
 	tristate "RedBoot partition table parsing"
 	---help---