Rename UK tones to GB tones

Previous CL which introduced UK tones was incorrect since "uk" is not a
valid ISO country code. This change checks for the "gb" country code
instead.

Change-Id: I1f99a7ec5dd24a112b2b1b486fe613f965fba7ff
Fix: 31003209
diff --git a/include/media/ToneGenerator.h b/include/media/ToneGenerator.h
index a419e17..9fd5f61 100644
--- a/include/media/ToneGenerator.h
+++ b/include/media/ToneGenerator.h
@@ -193,8 +193,8 @@
         TONE_JAPAN_DIAL,            // Dial tone: 400Hz, continuous
         TONE_JAPAN_BUSY,            // Busy tone: 400Hz, 500ms ON, 500ms OFF...
         TONE_JAPAN_RADIO_ACK,       // Radio path acknowlegment: 400Hz, 1s ON, 2s OFF...
-        // UK Supervisory tones
-        TONE_UK_RINGTONE,           // Ring Tone: A 400Hz + 450Hz tone repeated in a 0.4s on, 0.2s off, 0.4s on, 2.0s off pattern.
+        // GB Supervisory tones
+        TONE_GB_RINGTONE,           // Ring Tone: A 400Hz + 450Hz tone repeated in a 0.4s on, 0.2s off, 0.4s on, 2.0s off pattern.
         // AUSTRALIA Supervisory tones
         TONE_AUSTRALIA_RINGTONE,    // Ring tone: A 400Hz + 450Hz tone repeated in a 0.4s on, 0.2s off, 0.4s on, 2.0s off pattern.
         TONE_AUSTRALIA_BUSY,        // Busy tone: 425 Hz repeated in a 0.375s on, 0.375s off pattern.
@@ -206,7 +206,7 @@
     enum region {
         ANSI,
         JAPAN,
-        UK,
+        GB,
         AUSTRALIA,
         CEPT,
         NUM_REGIONS