[source] ramips: simplify ubnt-erx-sfp device definition

[LEDE Commits]

neoraider pushed a commit to source.git, branch master:
https://git.lede-project.org/4b32d66216b4772cd29d34175d421eccc59d8d09

commit 4b32d66216b4772cd29d34175d421eccc59d8d09
Author: Matthias Schiffer <mschiffer at universe-factory.net>
AuthorDate: Thu Jul 6 19:44:44 2017 +0200

    ramips: simplify ubnt-erx-sfp device definition
    
    Most of the ubnt-erx definition can be reused; the package removals in
    DEVICE_PACKAGES have become redundant after d17cb4a68a45 "ramips: purge
    default packages on MT7621".
    
    Signed-off-by: Matthias Schiffer <mschiffer at universe-factory.net>
---
 target/linux/ramips/image/mt7621.mk | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/target/linux/ramips/image/mt7621.mk b/target/linux/ramips/image/mt7621.mk
index 95d837b..940b9d5 100644
--- a/target/linux/ramips/image/mt7621.mk
+++ b/target/linux/ramips/image/mt7621.mk
@@ -185,15 +185,10 @@ endef
 TARGET_DEVICES += ubnt-erx
 
 define Device/ubnt-erx-sfp
+  $(Device/ubnt-erx)
   DTS := UBNT-ERX-SFP
-  FILESYSTEMS := squashfs
-  KERNEL_SIZE := 3145728
-  KERNEL := $(KERNEL_DTB) | uImage lzma
-  IMAGES := sysupgrade.tar
-  KERNEL_INITRAMFS := $$(KERNEL) | ubnt-erx-factory-image $(KDIR)/tmp/$$(KERNEL_INITRAMFS_PREFIX)-factory.tar
-  IMAGE/sysupgrade.tar := sysupgrade-tar | append-metadata
   DEVICE_TITLE := Ubiquiti EdgeRouter X-SFP
-  DEVICE_PACKAGES := -kmod-mt76 -kmod-rt2x00-lib -kmod-mac80211 -kmod-cfg80211 -wpad-mini -iwinfo kmod-i2c-algo-pca kmod-gpio-pca953x kmod-i2c-gpio-custom
+  DEVICE_PACKAGES += kmod-i2c-algo-pca kmod-gpio-pca953x kmod-i2c-gpio-custom
 endef
 TARGET_DEVICES += ubnt-erx-sfp