Get rid of [now] superfluous HexAdapter

With the introduction of using osmocom.construct.{Bytes,GreedyBytes}
in Change-Id I1c8df6350c68aa408ec96ff6cd1e405ceb1a4fbb we don't have a
need for wrapping each instance of Bytes or GreedyBytes into a
HexAdapter anymore.  The osmocom.construct.{Bytes,GreedyBytes} will
automatically perform the related hex-string-to-bytes conversion if
needed - and during printing we have osmocom.utils.JsonEncoder that
makes sure to convert any bytes type to a hex-string.

Change-Id: I9c77e420c314f5e74458628dc4e767eab6d97123

pySim/ts_31_103.py

@@ -167,7 +167,7 @@ class EF_GBABP(TransparentEF):
 class EF_GBANL(LinFixedEF):
     class NAF_ID(BER_TLV_IE, tag=0x80):
         _construct = Struct('fqdn'/Utf8Adapter(Bytes(this._.total_len-5)),
-                            'ua_spi'/HexAdapter(Bytes(5)))
+                            'ua_spi'/Bytes(5))
     class B_TID(BER_TLV_IE, tag=0x81):
         _construct = Utf8Adapter(GreedyBytes)
     # pylint: disable=undefined-variable