mb/google/fizz: Comment variant names in Kconfig

Refer to CL:1043916

BUG=none
BRANCH=none
TEST=none

Change-Id: I3fbbbcac334646f68b8b9fd38fbb529d9e833581
Signed-off-by: David Wu <David_Wu@quanta.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/29464
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/mainboard/google/fizz/Kconfig.name

@@ -1,7 +1,9 @@
+comment "Fizz"
+
 config BOARD_GOOGLE_FIZZ
-	bool "Fizz"
+	bool "->  Fizz"
 	select BOARD_GOOGLE_BASEBOARD_FIZZ
 
 config BOARD_GOOGLE_KARMA
-	bool "Karma"
+	bool "->  Karma"
 	select BOARD_GOOGLE_BASEBOARD_FIZZ