bootstat: label Mediatek boot reasons

Comment which strings come from Mediatek devices to aid maintenance.

Test: compile
Bug: 74595769
Bug: 63736262
Change-Id: Ic60970bcbbb389e4158ee691c4c81e6514d3b870
diff --git a/bootstat/bootstat.cpp b/bootstat/bootstat.cpp
index c091ff7..edec9e2 100644
--- a/bootstat/bootstat.cpp
+++ b/bootstat/bootstat.cpp
@@ -140,7 +140,7 @@
     {"mba_err", 13},
     {"Watchdog", 14},
     {"Panic", 15},
-    {"power_key", 16},
+    {"power_key", 16},  // Mediatek
     {"power_on", 17},
     {"Reboot", 18},
     {"rtc", 19},
@@ -203,13 +203,13 @@
     {"shutdown,hibernate", 74},  // Suspend to DISK
     {"power_on_key", 75},
     {"reboot_by_key", 76},
-    {"wdt_by_pass_pwk", 77},
+    {"wdt_by_pass_pwk", 77},  // Mediatek
     {"reboot_longkey", 78},
     {"powerkey", 79},
-    {"usb", 80},
-    {"wdt", 81},
-    {"tool_by_pass_pwk", 82},
-    {"2sec_reboot", 83},
+    {"usb", 80},               // Mediatek
+    {"wdt", 81},               // Mediatek
+    {"tool_by_pass_pwk", 82},  // Mediatek
+    {"2sec_reboot", 83},       // Mediatek
     {"reboot,by_key", 84},
     {"reboot,longkey", 85},
     {"reboot,2sec", 86},  // Deprecate in two years, replaced with cold,rtc,2sec
@@ -276,10 +276,10 @@
     {"software_master", 147},
     {"cold,charger", 148},
     {"cold,rtc", 149},
-    {"cold,rtc,2sec", 150},
-    {"reboot,tool", 151},
-    {"reboot,wdt", 152},
-    {"reboot,unknown", 153},
+    {"cold,rtc,2sec", 150},   // Mediatek
+    {"reboot,tool", 151},     // Mediatek
+    {"reboot,wdt", 152},      // Mediatek
+    {"reboot,unknown", 153},  // Mediatek
     {"kernel_panic,audit", 154},
     {"kernel_panic,atomic", 155},
     {"kernel_panic,hung", 156},