package/gcc: remove nios2 handling

Buildroot internal toolchain backend for nios2 was removed, so
remove nios2 handling for gcc package.

Signed-off-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Julien Olivain <ju.o@free.fr>

package/gcc/gcc.mk

@@ -293,11 +293,6 @@ HOST_GCC_COMMON_CONF_OPTS += \
 	--with-long-double-128
 endif
 
-# allow to build gcc 14.x
-ifeq ($(BR2_nios2),y)
-HOST_GCC_COMMON_CONF_OPTS += --enable-obsolete
-endif
-
 HOST_GCC_COMMON_TOOLCHAIN_WRAPPER_ARGS += -DBR_CROSS_PATH_SUFFIX='".br_real"'
 
 # For gcc-initial, we need to tell gcc that the C library will be