meta-ampere: mtjade: remove redundant mtjade string

The meta-ampere/meta-jade folder contains features for Mt.Jade platform
which might support various chassis. Having :mtjade is redundant and
will limit features to work only with "standard mtjade".
This commit removes this string so that additional MACHINEs based on
Mt.Jade can work.

Signed-off-by: Thang Q. Nguyen <thang@os.amperecomputing.com>
Change-Id: If57acd557d678b8834f0c77f98855277e4eee844
diff --git a/meta-ampere/meta-jade/recipes-kernel/linux/linux-aspeed_%.bbappend b/meta-ampere/meta-jade/recipes-kernel/linux/linux-aspeed_%.bbappend
index f10b289..bd66ef4 100644
--- a/meta-ampere/meta-jade/recipes-kernel/linux/linux-aspeed_%.bbappend
+++ b/meta-ampere/meta-jade/recipes-kernel/linux/linux-aspeed_%.bbappend
@@ -1,6 +1,6 @@
-FILESEXTRAPATHS:prepend:mtjade := "${THISDIR}/${PN}:"
+FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
 
 SRC_URI += " \
-    file://${MACHINE}.cfg \
-"
+            file://mtjade.cfg \
+           "