UBI: make tests modes dynamic

Similarly to the debugging checks and message, make the test modes
be dynamically selected via the "debug_tsts" module parameter or
via the "/sys/module/ubi/parameters/debug_tsts" sysfs file. This
is consistent with UBIFS as well.

And now, since all the Kconfig knobs became dynamic, we can remove
the Kconfig.debug file completely.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/Kconfig

@@ -52,6 +52,12 @@ config MTD_UBI_GLUEBI
 	   work on top of UBI. Do not enable this unless you use legacy
 	   software.
 
-source "drivers/mtd/ubi/Kconfig.debug"
+config MTD_UBI_DEBUG
+	bool "UBI debugging"
+	depends on SYSFS
+	select DEBUG_FS
+	select KALLSYMS_ALL if KALLSYMS && DEBUG_KERNEL
+	help
+	  This option enables UBI debugging.
 
 endif # MTD_UBI