cml1: Move find_cfgs() helper to cml1.bbclass

u-boot.inc and busybox.inc contain identical copies of this little
helper. They both inherit the cml1 class and use cml1_do_configure
right after having used this helper, and other recipes that want to
write similar logic for doing Kconfig via fragments will also need it
or something equivalent.

(From OE-Core rev: af687c9137a3e8efe48afa6fd12866cf656ae913)

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/cml1.bbclass

@@ -1,3 +1,13 @@
+# returns all the elements from the src uri that are .cfg files
+def find_cfgs(d):
+    sources=src_patches(d, True)
+    sources_list=[]
+    for s in sources:
+        if s.endswith('.cfg'):
+            sources_list.append(s)
+
+    return sources_list
+
 cml1_do_configure() {
 	set -e
 	unset CFLAGS CPPFLAGS CXXFLAGS LDFLAGS