unicode: clean up the Kconfig symbol confusion

Turn the CONFIG_UNICODE symbol into a tristate that generates some always
built in code and remove the confusing CONFIG_UNICODE_UTF8_DATA symbol.

Note that a lot of the IS_ENABLED() checks could be turned from cpp
statements into normal ifs, but this change is intended to be fairly
mechanic, so that should be cleaned up later.

Fixes: 2b3d047870 ("unicode: Add utf8-data module")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

fs/unicode/Kconfig

@@ -3,21 +3,13 @@
 # UTF-8 normalization
 #
 config UNICODE
-	bool "UTF-8 normalization and casefolding support"
+	tristate "UTF-8 normalization and casefolding support"
 	help
 	  Say Y here to enable UTF-8 NFD normalization and NFD+CF casefolding
-	  support.
-
-config UNICODE_UTF8_DATA
-	tristate "UTF-8 normalization and casefolding tables"
-	depends on UNICODE
-	default UNICODE
-	help
-	  This contains a large table of case foldings, which can be loaded as
-	  a separate module if you say M here.  To be on the safe side stick
-	  to the default of Y.  Saying N here makes no sense, if you do not want
-	  utf8 casefolding support, disable CONFIG_UNICODE instead.
+	  support.  If you say M here the large table of case foldings will
+	  be a separate loadable module that gets requested only when a file
+	  system actually use it.
 
 config UNICODE_NORMALIZATION_SELFTEST
 	tristate "Test UTF-8 normalization support"
-	depends on UNICODE_UTF8_DATA
+	depends on UNICODE

fs/unicode/Makefile

@@ -1,8 +1,10 @@
 # SPDX-License-Identifier: GPL-2.0
 
-obj-$(CONFIG_UNICODE) += unicode.o
+ifneq ($(CONFIG_UNICODE),)
+obj-y			+= unicode.o
+endif
+obj-$(CONFIG_UNICODE)	+= utf8data.o
 obj-$(CONFIG_UNICODE_NORMALIZATION_SELFTEST) += utf8-selftest.o
-obj-$(CONFIG_UNICODE_UTF8_DATA) += utf8data.o
 
 unicode-y := utf8-norm.o utf8-core.o