binutils: remove leftover version definitions

Following d4839ffcab70f2496673e5b376f4c0d492260396 ("binutils: remove
2.20.1, 2.21 and 2.23.1"), Config.in.host contains unneeded
definitions of BR2_BINUTILS_VERSION for no longer existing
versions. This patch fixes that.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/binutils/Config.in.host

@@ -35,11 +35,8 @@ config BR2_BINUTILS_VERSION
 	string
 	default "2.18-avr32-1.0.1" if BR2_BINUTILS_VERSION_2_18_AVR32_1_0_1
 	default "arc-4.8-R3"	if BR2_arc
-	default "2.20.1"	if BR2_BINUTILS_VERSION_2_20_1
-	default "2.21"		if BR2_BINUTILS_VERSION_2_21
 	default "2.21.1"	if BR2_BINUTILS_VERSION_2_21_1
 	default "2.22"		if BR2_BINUTILS_VERSION_2_22
-	default "2.23.1"	if BR2_BINUTILS_VERSION_2_23_1
 	default "2.23.2"	if BR2_BINUTILS_VERSION_2_23_2
 	default "2.24"		if BR2_BINUTILS_VERSION_2_24