external: Remove external/shared link targets
external: Remove external/shared link targets

These are already defined just like we need them in common/rules.mk

Signed-off-by: Brad Bishop <713d098c0be4c8fd2bf36a94cd08699466677ecd@fuzziesquirrel.com>
Reviewed-by: Joel Stanley <4816dabf8db1bc6cac35b3a24cab2ff844b5b0c7@jms.id.au>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

open-power/skiboot,stewart-ibm/skiboot,mikey/skiboot,mikey/skiboot,shenki/skiboot,mikey/skiboot,qemu/skiboot,qemu/skiboot,legoater/skiboot,shenki/skiboot,shenki/skiboot,qemu/skiboot,shenki/skiboot,qemu/skiboot,stewart-ibm/skiboot,open-power/skiboot,open-power/skiboot,legoater/skiboot,open-power/skiboot,legoater/skiboot,shenki/skiboot,legoater/skiboot,stewart-ibm/skiboot,open-power/skiboot,legoater/skiboot,qemu/skiboot