mini2440_defconfig: fix getty config

BR2_TARGET_GENERIC_GETTY_TTYSAC0 is no more.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

configs/mini2440_defconfig

@@ -3,7 +3,8 @@ BR2_arm=y
 BR2_arm920t=y
 
 # Serial port
-BR2_TARGET_GENERIC_GETTY_TTYSAC0=y
+BR2_TARGET_GENERIC_GETTY=y
+BR2_TARGET_GENERIC_GETTY_PORT="ttySAC0"
 
 # Filesystem
 BR2_TARGET_ROOTFS_JFFS2=y