arch/arm: fix-up the ARM Kconfig warning

Kconfig does not accepts that a symbol that is part of a choice
be affected a default value.

Fix this by introducing a dummy EABI symbol, and make the real
EABI symbol a prompt-less option that depends on !OABI.

[Peter: drop arm dependency, rename to EABI_CHOICE]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Peter Korsgaard <jacmet@uclibc.org>
Cc: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

arch/Config.in.arm

@@ -76,7 +76,7 @@ choice
 	  Note:
 	    Using OABI is discouraged.
 
-config BR2_ARM_EABI
+config BR2_ARM_EABI_CHOICE
 	bool "EABI"
 config BR2_ARM_OABI
 	bool "OABI"
@@ -84,8 +84,8 @@ config BR2_ARM_OABI
 endchoice
 
 config BR2_ARM_EABI
-	default y
-	depends on !BR2_DEPRECATED
+	def_bool y
+	depends on !BR2_ARM_OABI
 
 config BR2_ARM_ENABLE_NEON
 	bool "Enable NEON SIMD extension support"