bitbake: data_smart: Use regex consistently for override matching

One section of the code is enforcing lowercase overrides, the other
is allowing numeric characters. We should be consistent with one or
the other.

(Bitbake rev: df5b3b841fd8d6a652d643e9ae2bba09d60043e0)

Signed-off-by: 张忠山 <zzs213@126.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/data_smart.py

@@ -720,7 +720,7 @@ class DataSmart(MutableMapping):
         if ':' in var:
             override = var[var.rfind(':')+1:]
             shortvar = var[:var.rfind(':')]
-            while override and override.islower():
+            while override and __override_regexp__.match(override):
                 try:
                     if shortvar in self.overridedata:
                         # Force CoW by recreating the list first