PEL: Add altitude PEL registry entries

These will only be used on systems that use PELs and have the virtual
altitude sensor. The errors come from the sensor-monitor app.

Signed-off-by: Rashmica Gupta <rashmica.g@gmail.com>
Change-Id: I5fec3ec86a084f8c62f52194f2826c0565be32eb
diff --git a/extensions/openpower-pels/pel_values.cpp b/extensions/openpower-pels/pel_values.cpp
index 17e1d50..1a0343b 100644
--- a/extensions/openpower-pels/pel_values.cpp
+++ b/extensions/openpower-pels/pel_values.cpp
@@ -229,7 +229,7 @@
     {"usb_pgood", "USBPGD"},          {"ambient_temp", "AMBTEMP"},
     {"ambient_temp_back", "AMBBACK"}, {"ambient_perf_loss", "AMBPERF"},
     {"ac_module", "ACMODUL"},         {"fan_cable", "FANCBL"},
-    {"cable_continued", "CBLCONT"}};
+    {"cable_continued", "CBLCONT"},   {"altitude", "ALTTUDE"}};
 
 PELValues::const_iterator findByValue(uint32_t value, const PELValues& fields)
 {