UBI: do not select KALLSYMS_ALL

All UBI needs is to make sure we stacktraces when UBI debugging
is enabled. It is enough to select KALLSYMS for this, KALLSYMS_ALL
is not necessary.

And the current Kconfig line we have:

select KALLSYMS_ALL if KALLSYMS && DEBUG_KERNEL

is just too complex to be sane and right. But this "if" part there
is needed to prevent "unmet direct dependency" warnings, because
KALLSYMS_ALL depends on KALLSYMS and DEBUG_KERNEL, so we cannot
just select KALLSYMS_ALL.

Anyway, this feels messy, and we do not seem to really need KALLSYMS_ALL,
so select KALLSYMS instead.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>

drivers/mtd/ubi/Kconfig

@@ -56,7 +56,7 @@ config MTD_UBI_DEBUG
 	bool "UBI debugging"
 	depends on SYSFS
 	select DEBUG_FS
-	select KALLSYMS_ALL if KALLSYMS && DEBUG_KERNEL
+	select KALLSYMS
 	help
 	  This option enables UBI debugging.