PEL: Add APIs to look up device path callouts

This commit adds the interfaces device_callouts::getCallouts() and
device_callouts::getI2CCallouts() that will be used to look up the FRU
callouts to add to PELs for errors stemming from accessing devices,
either by a sysfs path, or in the case of the latter interface an I2C
bus and address.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I573d04632fd9fc6356a0ff53f85c2a2c13038962
diff --git a/extensions/openpower-pels/openpower-pels.mk b/extensions/openpower-pels/openpower-pels.mk
index cd1ab10..8e5893e 100644
--- a/extensions/openpower-pels/openpower-pels.mk
+++ b/extensions/openpower-pels/openpower-pels.mk
@@ -23,6 +23,7 @@
 	extensions/openpower-pels/callout.cpp \
 	extensions/openpower-pels/callouts.cpp \
 	extensions/openpower-pels/data_interface.cpp \
+	extensions/openpower-pels/device_callouts.cpp \
 	extensions/openpower-pels/extended_user_header.cpp \
 	extensions/openpower-pels/failing_mtms.cpp \
 	extensions/openpower-pels/fru_identity.cpp \