libpldm: Change hexadecimal literals to lowercase

As per a comment at [1].

The change was generated with the following:

```
sed -Ei 's/0[xX]([0-9]*[A-F][0-9]*)+/\L\0/g' $(git ls-files)
```

[1]: https://gerrit.openbmc.org/c/openbmc/libpldm/+/69192

Change-Id: Ib0a41dfaf626aec3167e773262883f9c1de797b2
Signed-off-by: Pavithra Barithaya <pavithra.b@ibm.com>
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/include/libpldm/oem/ibm/fru.h b/include/libpldm/oem/ibm/fru.h
index e95500d..32e7138 100644
--- a/include/libpldm/oem/ibm/fru.h
+++ b/include/libpldm/oem/ibm/fru.h
@@ -10,10 +10,10 @@
 #include <stdint.h>
 
 enum pldm_oem_ibm_fru_field_type {
-	PLDM_OEM_FRU_FIELD_TYPE_IANA = 0X01,
-	PLDM_OEM_FRU_FIELD_TYPE_RT = 0X02,
-	PLDM_OEM_FRU_FIELD_TYPE_PCIE_CONFIG_SPACE_DATA = 0XFD,
-	PLDM_OEM_FRU_FIELD_TYPE_LOCATION_CODE = 0XFE,
+	PLDM_OEM_FRU_FIELD_TYPE_IANA = 0x01,
+	PLDM_OEM_FRU_FIELD_TYPE_RT = 0x02,
+	PLDM_OEM_FRU_FIELD_TYPE_PCIE_CONFIG_SPACE_DATA = 0xfd,
+	PLDM_OEM_FRU_FIELD_TYPE_LOCATION_CODE = 0xfe,
 };
 
 #ifdef __cplusplus