Add decode of pcie device class

This commit makes two major changes.  First, the device class tables
were being decoded incorrectly as LSB-first. This changes them to
MSB-first.

Second, once this value is correct decode the tables to a string name
making it much easier for users to identify a specific device that
caused a PCIe error.

Note: The majority of the mode lookup table was created by LLM.  The
entries have been manually reviewed for correctness and completeness.

Change-Id: I61bc813dbab39ca6116046e302dafca9fbbb0893
Signed-off-by: Ed Tanous <etanous@nvidia.com>
diff --git a/tests/ir-tests.c b/tests/ir-tests.c
index a0a0db1..cfbaffb 100644
--- a/tests/ir-tests.c
+++ b/tests/ir-tests.c
@@ -373,6 +373,8 @@
 	int cper_buf_hex_len =
 		to_hex((unsigned char *)cper_buf, cper_buf_size, &cper_buf_hex);
 
+	printf("%.*s\n", cper_buf_hex_len, cper_buf_hex);
+	printf("%.*s\n", buf_hex_len, buf_hex);
 	assert(buf_hex_len == cper_buf_hex_len);
 	assert(memcmp(buf_hex, cper_buf_hex, buf_hex_len) == 0);