lib: Create a new Kconfig option for charset conversion

Rather than looking at two KConfig options in the Makefile, create a new
Kconfig option for compiling lib/charset.c

Enable it for UFS also, which needs this support.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

lib/Kconfig

@@ -40,6 +40,14 @@ config CC_OPTIMIZE_LIBS_FOR_SPEED
 
 	  If unsure, say N.
 
+config CHARSET
+	bool
+	default y if UT_UNICODE || EFI_LOADER || UFS
+	help
+	  Enables support for various conversions between different
+	  character sets, such as between unicode representations and
+	  different 'code pages'.
+
 config DYNAMIC_CRC_TABLE
 	bool "Enable Dynamic tables for CRC"
 	help

lib/Makefile

@@ -25,7 +25,7 @@ obj-$(CONFIG_AES) += aes/
 obj-$(CONFIG_$(SPL_TPL_)BINMAN_FDT) += binman.o
 
 ifndef API_BUILD
-ifneq ($(CONFIG_UT_UNICODE)$(CONFIG_EFI_LOADER),)
+ifneq ($(CONFIG_CHARSET),)
 obj-y += charset.o
 endif
 endif