arch/m68k: get rid of BR2_GCC_TARGET_TUNE

On m68k, we are passing the exact same values of BR2_GCC_TARGET_ARCH
and BR2_GCC_TARGET_TUNE, which is redundant. Therefore, this commit
removes the usage of BR2_GCC_TARGET_TUNE on m68k.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

arch/Config.in.m68k

@@ -7,14 +7,6 @@ config BR2_ENDIAN
 config BR2_ARCH_HAS_ATOMICS
 	default y
 
-config BR2_GCC_TARGET_TUNE
-	default "68000"		if BR2_m68k_68000
-	default "68010"		if BR2_m68k_68010
-	default "68020"		if BR2_m68k_68020
-	default "68030"		if BR2_m68k_68030
-	default "68040"		if BR2_m68k_68040
-	default "68060"		if BR2_m68k_68060
-
 config BR2_GCC_TARGET_ARCH
 	default "68000"		if BR2_m68k_68000
 	default "68010"		if BR2_m68k_68010